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TIE fighter

The TIE fighter or Twin Ion Engine fighter is a series of fictional starfighters featured in the Star Wars universe. TIE fighters are depicted as fast, agile, yet fragile starfighters produced by Sienar Fleet Systems for the Galactic Empire and by Sienar-Jaemus Fleet Systems for the First Order and the Sith Eternal. TIE fighters and other TIE craft appear in Star Wars films, television shows, and throughout the Star Wars expanded universe. Several TIE fighter replicas and toys, as well as a TIE flight simulator, have been produced and sold by many companies.

Origin and design
Colin Cantwell created the concept model that established the TIE fighter's ball-cockpit and hexagonal panels design for Star Wars (1977). Star Wars creator George Lucas liked the basic design consisting of two panels connected by a stick with a ball-shaped cockpit, but Cantwell's concept had few details. Joe Johnston created additional details, such as the cockpit window and the attachment points between the solar panels and the hull.

Initially given a blue color scheme, the TIE fighter models for the first film were grey to film better against a bluescreen; TIE fighters in The Empire Strikes Back (1980) and Return of the Jedi (1983) shifted back to being a muted blue. Sound designer Ben Burtt created the distinctive sound of the TIE fighter in flight by combining an elephant call with a car driving on wet pavement. In the book The Sounds of Star Wars, the engine roar is likened to German Junker Ju 87 "Stuka" bombers, which used sirens to frighten civilians during air raids. This could have been a possible inspiration for the sound. Combat scenes between TIE fighters and the Millennium Falcon and Rebel Alliance X-wing fighters in Star Wars were meant to be reminiscent of World War II dogfight footage; editors used World War II air combat clips as placeholders while Industrial Light & Magic completed the movie's special effects. Darth Vader's distinct TIE Advanced x1 in Star Wars was designed to make it instantly recognizable, and the TIE Interceptors featured in Return of the Jedi were designed to look fast, deadly, sleek and frightening.

The Jedi starfighter, created for Revenge of the Sith (2005), was designed to bridge the appearance of the Jedi starfighter in Attack of the Clones (2002) and the TIE fighter design from the original trilogy. The V-wing starfighter, seen at the end of Revenge of the Sith, also makes the distinctive TIE fighter sound when flying by a Star Destroyer. Dark Horse Comics' Sean Cooke designed the TIE predator for Star Wars: Legacy (2006), set 130 years after the events of Star Wars, to appear both reminiscent of and more advanced than the original TIE fighter.

Designers for The Force Awakens (2015) had numerous discussions about how much to "update" the TIE fighter for the first sequel film set 30 years after Return of the Jedi. They retained the starfighter's design but altered its aesthetic to suggest improvements to the vessel's manufacturing process and materials.

Depiction
Star Wars literature states that Grand Moff Tarkin commissioned Sienar Fleet Systems to design and manufacture the Twin Ion Engine line edition (TIE/ln) space superiority starfighter and most TIE variants. Tarkin specified that the TIE had to be fast, maneuverable, energy-efficient, and inexpensive; simply put they are meant to be easily mass-produced and engage in swarm tactics, with the expectation of being expendable assets that would be lost in combat. To meet these requirements, Sienar incorporated aspects of the V-wing and Jedi interceptor into the new starfighter.

TIE fighters have two hexagonal wings fitted with solar panels which power a twin ion engine (TIE) system that accelerates ionized gases at a substantial fraction of lightspeed along almost any vector, affording the ships tremendous speed and maneuverability albeit with limited fuel reserves. These wings are also structurally sound enough to double as landing gear and feature repulsorlifts for take-off and landing, though TIE fighters are designed to be launched and recovered by cycling storage racks used by Imperial starships and garrisons. The TIE fighter's primary weapons are a pair of laser cannons tied to a secondary generator and mated with an advanced targeting computer which assists the pilot in hitting other fast-moving starfighters. The fighter does not possess deflector shields, and while its light armoring is proof against small arms and glancing micrometeoroids a direct hit from a laser cannon will destroy it, encouraging pilots to shoot first and make their shots count. The TIE fighter also lacks a hyperdrive, not only to save on weight and cost but to discourage defection. Although the TIE fighter's cockpit is pressurized and equipped with oxygen scrubbers to prevent corrosion, it doesn't contain any life-support systems, requiring pilots to wear special flight suits. TIE fighters are equipped with ejection seats, though in older Legends sources there was disagreement on this issue.

Star Wars literature also holds that TIE fighter pilots are considered an elite group within the Imperial Navy, relying on their quick reflexes and fearlessness to survive multiple tours of duty. Training involves hundreds of flight hours learning to coordinate as a team and intense psychological conditioning to put the accomplishment of their mission above other considerations. As such most TIE fighter pilots have a life expectancy of less than a year. TIE fighter pilots wear self-contained flight suits with life-support systems connected to reinforced vacuum-sealed flight helmets. These helmets feature ship-linked communications and displays.

TIE variants
In addition to the standard TIE/ln fighter (also available as the TIE Light Duty training craft, as seen in the Jump to Lightspeed expansion pack to Star Wars Galaxies), a variety of other TIE craft appear throughout the films.
 * In Star Wars film and television

Imperial variants

 * TIE Advanced x1: Darth Vader flies a TIE Advanced x1 (or just "TIE/x1") in many media, most notably in the original Star Wars during the climatic Death Star battle. According to background material, the limited-run TIE Advanced x1 was designed to Vader's personal specifications and was only flown by himself and select Imperial pilots.  Compared to the TIE fighter it is faster and more maneuverable with greater structural integrity, equipped with a deflector shield, hyperdrive, reinforced armor-plated hull and improved SFS L-s9.3 laser cannons.  The "bent-wing" configuration was intended to improve energy collection while maintaining the same speed and maneuverability.
 * TIE/sa bomber: Introduced in The Empire Strikes Back, TIE/sa bombers are seen bombing asteroids in the hunt for the Millennium Falcon. The design stems from an unused "TIE boarding craft" concept originally developed for A New Hope. The TIE bomber's double-hull design led ILM's modelmakers to dub the ship a "double chili dog" fighter. The TIE/sa, or TIE Surface Assault Bomber, was designed within the Star Wars universe for the Imperial Navy to conduct surgical strikes against targets in space or on planetary surfaces.  It features two cylindrical pods: the starboard-side pod housing the pilot in a pressurized cockpit with a pair of L-s1 laser cannons, and a port-side pod carrying two bomb bays that can launch a variety of ordnance including missiles, bombs and orbital mines.  Its "bent-wing" configuration increased the energy-collection surface area to match the bomber's power requirements while a reinforced hull allowed the bomber survive back-blast during atmospheric bombing.
 * TIE/sh shuttle: Also featured in The Empire Strikes Back, a TIE/sh shuttle is seen ferrying Captain Needa (Michael Culver) to Darth Vader's Super Star Destroyer. Like the TIE/sa bomber, this shuttle design stems from an unused "TIE boarding craft" concept developed for A New Hope. Known also within the setting as the TIE Command Shuttle, the craft was based on the TIE/sa bomber but replaced the bombardier pod with a luxurious cabin suitable for Imperial dignitaries and naval officers.  In the event the vessel is attacked, the TIE shuttle carries a pair of laser cannons and deflector shields.
 * TIE/IN interceptor: TIE/IN interceptor – faster TIE fighters with dagger-shaped wings in the forward profile of those of the TIE Advanced and four laser cannons – appear at various points in Return of the Jedi. Two scales of TIE interceptor models were used during filming. Their in-universe origin was to meet the Empire's requirement for a fighter superior to the Rebellion's X-wing and Y-wing fleet when it was determined a full production run of the TIE Advanced x1 would be too expensive.  Faster and more maneuverable than a standard TIE fighter, these interceptors are also better armed with wingtip-mounted L-s9.3 laser cannons with the option to carry two more under the cockpit.
 * TIE Advanced v1: Meant to appear as the prototype precursor to Vader's TIE Advanced x1, the TIE Advanced v1 featured in Star Wars Rebels as craft piloted by the Empire's Inquisitors. The v1's variable-geometry wings, like Darth Maul's shuttle Scimitar ' s, were inspired by Ralph McQuarrie's original sketches for the x1.  The fighters' fictional origin is inspired by the Jedi interceptor flown during the Clone Wars, as seen by its heavily-armored wings that fold inward.  With laser cannons and ion engines more powerful than the TIE fighter, the TIE Advanced v1 also features a projectile launcher with a 20 missile magazine, deflector shields and pressurized cockpit. The TIE/v1 debuted in the Rebels Season 1 episode "Empire Day", which featured its maiden flight, but a very similar spacecraft (most likely intended to be the same) was described in the 2014 book Star Wars: Imperial Handbook: A Commander's Guide, which has been confirmed to fall into the Legends continuity, which had by then been decanonized.
 * TIE/d Defender: The TIE/d Defender made its television debut in Star Wars Rebels, although it first appeared in the 1994 space flight simulator Star Wars: TIE Fighter as player-pilotable craft. In the previous Star Wars Legends continuity, the TIE Defender was originally designed by Admiral Zaarin, who in the 1994 game would betray the Empire and have to be defeated by the player character. Its background was later changed in Star Wars Rebels to being designed personally by Grand Admiral Thrawn.  Classified as a fighter-bomber, its unique tri-wing design gives it better visibility than a TIE interceptor while making it faster than all previous TIE models.  Each wing is equipped with maneuvering jets and a pair of L-s9.3 laser cannons, with another pair and twin projectile launchers fitted on the cockpit pod.  The TIE/d Defender also carries deflector shields and a hyperdrive.
 * TIE/sk x1 Striker: The TIE/sk x1 experimental air superiority fighter, also known as the TIE Striker, made its first appearance in Rogue One defending the Imperial base on Scarif. Background material on the model describes how it was specifically designed for atmospheric patrols of Imperial ground installations because of the standard TIE fighter's disadvantage in atmospheric combat. With its more aerodynamic design and specialized repulsorlift engines, the TIE Striker can fly faster than a TIE fighter or X-wing in an atmosphere and is heavily armed with four L-s9.3 laser cannons, two H-s1 heavy laser cannons, and a bomb bay.  Its spacious cockpit can hold a pilot and an optional gunner/bombardier.
 * TIE/rp Reaper: The TIE/rp Reaper Attack Lander also made its first appearance in Rogue One as support craft with a larger, more angular design that replaces the spherical cockpit found on most TIE fighters. Within the Star Wars universe, these craft were based on the TIE/sk x1 Striker with similar wing configuration but much larger to carry elite Imperial troops into battle.  The TIE/rp Reaper features armor plating, deflector shields and electronic countermeasures to ensure it can survive hostile airspace to deliver its cargo.  It also carries a hyperdrive for faster-than-light travel and a pair of L-s9.3 laser cannons.
 * TIE Boarding Craft: The TIE Boarding Craft made its theatrical appearance in Rogue One. The design was originally set to appear in the original Star Wars but was cut from the film and used as inspiration for the TIE bomber and TIE shuttle.  Background literature states that the TIE Boarding Craft shared many of the same features as the TIE bomber but with seating for twelve passengers and a boarding hatch equipped with laser cutters.  Other equipment included deflector shields, twin L-s1 laser cannons, twin H-s1 heavy laser cannons and missile launcher.
 * TIE reinforcement battery heavy starfighter: The TIE/rb, known also as the TIE Brute, first appeared in Solo: A Star Wars Story chasing the Millennium Falcon during the Kessel Run scene. Star Wars literature states that the TIE/rb was commissioned to help deal with pirates, smugglers and other outlaws operating in the Outer Rim.  Larger than a standard TIE fighter, the TIE/rb features heavier armor plating and carries a pair of H-s9.3 laser cannons – nearly twice as powerful as a TIE fighter's cannons – on a separate artillery pod.  Because it was sluggish to fly, the TIE Brute features an integrated droid intelligence to assist the pilot.
 * TIE Crawler: Also known as the Century Tank or the TIE Tank, the vehicle was a tank resembling a TIE fighter but equipped with treaded tracks.
 * Outland TIE fighter: The TIE Boarding Craft made its television appearance in The Mandalorian. Otherwise congruent to the appearance of a standard TIE fighter, the Outland TIE fighter's wings folded when landing on a levelled surface, dissimilar to that of an X-wing in an open position. In addition, landing gears were concealed inside the bottom of the cockpit to allow for ease of use and stability. The personal starfighter of Moff Gideon, flown by the Moff himself, was used by his Imperial remnant during the New Republic Era, though the Mandalorian bounty hunter Din Djarin took down the starfighter.

First Order variants

 * TIE/fo space superiority fighter: The Force Awakens features the First Order TIE/fo space superiority fighter, which is superficially similar to the Empire's original TIE fighter but with several technological upgrades. Built by Sienar-Jaemus Fleet Systems, it features superior firepower, speed and maneuverability with a pair of SJSF L-s9.6 laser cannons and twin SJFS P-s6 ion engines aided by superior solar cell wings and higher-capacity energy converters.  Perhaps the biggest difference is the fact that the TIE/fo features deflector shields – a recognition by the First Order that compared to the Galactic Empire it must take measures to safeguard its more limited supply of pilots.
 * TIE/sf space superiority fighter: Also featured in The Force Awakens is the TIE/sf fighter, one of which is stolen by Poe Dameron (Oscar Isaac) and Finn (John Boyega) as they escape the First Order. Piloted by members of the First Order Special Forces, this model is superior to the First Order's TIE/fo.  It is equipped with a hyperdrive, superior shielding, twin ion reactors, a pair of forward-facing L-s9.6 laser cannons, an aft Lb-14 dual heavy laser turret with full 360-degree rotation, and a missile/mag-pulse launcher.
 * TIE/ba interceptor: First appearing in Star Wars Resistance, the TIE/ba interceptor is a model of TIE interceptor deployed by the First Order. One ship was used by Major Elrik Vonreg during the late-New Republic era in his encounters with the New Republic and the Resistance.
 * TIE silencer: First appearing in Star Wars: The Last Jedi, the TIE/vn Silencer is the Interceptor-winged personal starfighter of Kylo Ren.
 * TIE whisper: Kylo Ren flies a custom-model TIE/wi fighter in The Rise of Skywalker.

Sith Eternal variants

 * TIE/dg starfighter: Also known as the Sith TIE fighter, the TIE Dagger featured in The Rise of Skywalker as a red triangular-wing model of TIE fighter forged in secret for forces operating under the reborn Darth Sidious.

A number of different TIE designs made their appearance in what is now considered Star Wars Legends, a separate continuity that was split off after Disney acquired the Star Wars franchise. The TIE/sa was the inspiration for the triple-hulled TIE lander, featured in Star Wars No. 60 and in Star Wars: Complete Locations. Red-modified TIE interceptors are also used by the Emperor's Royal Guards, as featured in Rage of the Wookiees, another expansion of Star Wars Galaxies.
 * In Star Wars Legends continuity

Additionally, LucasArts Star Wars video games introduce several TIE variants, such as the TIE Hunter starfighter in Rogue Squadron III and the TIE Mauler surface vehicle in Empire at War. The TIE/ad fighter (nicknamed "TIE Advanced" or "Avenger" in-game and derived from Vader's TIE Advanced x1 fighter) and TIE/D Defender — heavily upgraded derivatives of previous craft seen in the Star Wars universe — first appear in TIE Fighter as player-pilotable craft. The plot of Rebel Assault II revolves around destroying the Empire's ability to manufacture the cloaking TIE Phantom starfighter, and a campaign in X-Wing Alliance centers on destroying experimental remote-controlled TIE fighters.

Star Wars literature also introduces TIE varieties. TIE raptors attack Rogue Squadron in Solo Command. TYE wings – TIE fighter and Y-wing hybrids – appear both in I, Jedi and Rogue Squadron: Masquerade. Dark Horse's Dark Empire introduces both the droid-piloted TIE/D and the TIE crawler "century tank". West End Games' roleplaying sourcebooks introduce varieties that include the TIE/fc fire-control support ship, the TIE/gt ground-attack fighter, the TIE/rc reconnaissance vessel, and the TIE scout.

Cultural impact
A TIE fighter model used in filming the climax of Star Wars sold at auction for $350,000, and another TIE fighter from the film sold at auction for $402,500. Fans built a 16-foot-by-20-foot, 1,000-pound TIE fighter float to commemorate Star Wars ' thirtieth anniversary as part of the 2007 Gala Parade in Crystal Lake, Illinois. A Wired editor's creation of a TIE fighter model out of Starbucks cups and stirrers prompted the magazine to create a contest for its readers to submit their own art out of similar Starbucks material. io9 mocked the variety of TIE fighters in the franchise, listing four TIE models on its list of the eleven "silliest" Star Wars ships.

Kenner released TIE fighter and TIE interceptor toys during the original Star Wars trilogy's theatrical release, and Kenner's die-cast TIE bomber is a rare collector's item. Hasbro also released TIE fighter, TIE bomber, and TIE interceptor toys. Both Kenner and Hasbro also manufactured TIE fighter pilot action figures. Lego manufactured TIE fighter, TIE bomber, TIE interceptor, TIE defender, and TIE advanced models. Decipher and Wizards of the Coast published various TIE starfighter and TIE-related cards for the Star Wars Customizable Card Game and Star Wars Trading Card Game, respectively. In 2012, Fantasy Flight Games released Star Wars: X-Wing Miniatures Game, a miniatures game with pre-painted and to scale miniature X-wings and TIE fighters. In 1994, LucasArts released the TIE Fighter flight simulator, which casts the player as an Imperial pilot flying a variety of TIE starfighters. TIE starfighters and their variants are also playable in third- or first-person perspectives in several Star Wars titles.

In Sasuke (also known as Ninja Warrior), TIE Fighter (Japanese: タイファイター) was a obstacle that introduced in the 32nd competition as the second obstacle in the First Stage. Competitors must prop their hands and feet against a set of glass panels that much resemble to the two hexagonal solar energy-collecting wings of TIE Fighter, position themselves and slide down a track to reach the safety platform at the other side. Due to the expiration of the license before the 36th competition, the TIE Fighter was renamed the Wing Slider (Japanese: ウィングスライダー), and was redesigned to reflect this.

In 2018, a number of Star Wars starfighters had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. Of those studied, the TIE Fighter scored the worst with a drag coefficient of .98, which is only slightly better than a brick. Of the other TIE variants tested, the TIE interceptor was slightly better with a coefficient of .78, while the TIE Striker had the best at .48, though this did not compare favorably to the .02 drag coefficient of an F-4E Phantom. These poor results were rationalized with the in-universe explanations that drag coefficient plays no role in space travel, and that Star Wars fighters can use repulsorlifts and deflector shields to give themselves better flight profiles.

title: TIE fighter


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Insomnia

Insomnia, also known as sleeplessness, is a sleep disorder where people have trouble sleeping. They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, irritability, and a depressed mood. It may result in an increased risk of accidents of all kinds as well as problems focusing and learning. Insomnia can be short term, lasting for days or weeks, or long term, lasting more than a month. The concept of the word insomnia has two possibilities: insomnia disorder (ID) and insomnia symptoms, and many abstracts of randomized controlled trials and systematic reviews often underreport on which of these two possibilities the word insomnia refers to.

Insomnia can occur independently or as a result of another problem. Conditions that can result in insomnia include ADHD, psychological stress, chronic pain, heart failure, hyperthyroidism, heartburn, restless leg syndrome, menopause, certain medications, and drugs such as caffeine, nicotine, and alcohol. Other risk factors include working night shifts and sleep apnea. Diagnosis is based on sleep habits and an examination to look for underlying causes. A sleep study may be done to look for underlying sleep disorders. Screening may be done with two questions: "do you experience difficulty sleeping?" and "do you have difficulty falling or staying asleep?"

Although their efficacy as first line treatments is not unequivocally established, sleep hygiene and lifestyle changes are typically the first treatment for insomnia. Sleep hygiene includes a consistent bedtime, a quiet and dark room, exposure to sunlight during the day and regular exercise. Cognitive behavioral therapy may be added to this. While sleeping pills may help, they are sometimes associated with injuries, dementia, and addiction. These medications are not recommended for more than four or five weeks. The effectiveness and safety of alternative medicine is unclear.

Between 10% and 30% of adults have insomnia at any given point in time and up to half of people have insomnia in a given year. About 6% of people have insomnia that is not due to another problem and lasts for more than a month. People over the age of 65 are affected more often than younger people. Women are more often affected than men. Descriptions of insomnia occur at least as far back as ancient Greece.

Signs and symptoms

Symptoms of insomnia: Sleep onset insomnia is difficulty falling asleep at the beginning of the night, often a symptom of anxiety disorders. Delayed sleep phase disorder can be misdiagnosed as insomnia, as sleep onset is delayed to much later than normal while awakening spills over into daylight hours.
 * Difficulty falling asleep, including difficulty finding a comfortable sleeping position
 * Waking during the night, being unable to return to sleep and waking up early
 * Not able to focus on daily tasks, difficulty in remembering
 * Daytime sleepiness, irritability, depression or anxiety
 * Feeling tired or having low energy during the day
 * Trouble concentrating
 * Being irritable, acting aggressive or impulsive

It is common for patients who have difficulty falling asleep to also have nocturnal awakenings with difficulty returning to sleep. Two-thirds of these patients wake up in the middle of the night, with more than half having trouble falling back to sleep after a middle-of-the-night awakening.

Early morning awakening is an awakening occurring earlier (more than 30 minutes) than desired with an inability to go back to sleep, and before total sleep time reaches 6.5 hours. Early morning awakening is often a characteristic of depression. Anxiety symptoms may well lead to insomnia. Some of these symptoms include tension, compulsive worrying about the future, feeling overstimulated, and overanalyzing past events.

Poor sleep quality
Poor sleep quality can occur as a result of, for example, restless legs, sleep apnea or major depression. Poor sleep quality is defined as the individual not reaching stage 3 or delta sleep which has restorative properties.

Major depression leads to alterations in the function of the hypothalamic–pituitary–adrenal axis, causing excessive release of cortisol which can lead to poor sleep quality.

Nocturnal polyuria, excessive night-time urination, can also result in a poor quality of sleep.

Subjectivity
Some cases of insomnia are not really insomnia in the traditional sense, because people experiencing sleep state misperception often sleep for a normal amount of time. The problem is that, despite sleeping for multiple hours each night and typically not experiencing significant daytime sleepiness or other symptoms of sleep loss, they do not feel like they have slept very much, if at all. Because their perception of their sleep is incomplete, they incorrectly believe it takes them an abnormally long time to fall asleep, and they underestimate how long they stay asleep.

Causes
While insomnia can be caused by a number of conditions, it can also occur without any identifiable cause. This is known as Primary Insomnia. Primary Insomnia may also have an initial identifiable cause, but continues after the cause is no longer present. For example, a bout of insomnia may be triggered by a stressful work or life event. However the condition may continue after the stressful event has been resolved. In such cases, the insomnia is usually perpetuated by the anxiety or fear caused by the sleeplessness itself, rather than any external factors.

Symptoms of insomnia can be caused by or be associated with:
 * Sleep breathing disorders, such as sleep apnea or upper airway resistance syndrome
 * Use of psychoactive drugs (such as stimulants), including certain medications, herbs, caffeine, nicotine, cocaine, amphetamines, methylphenidate, aripiprazole, MDMA, modafinil, or excessive alcohol intake
 * Use of or withdrawal from alcohol and other sedatives, such as anti-anxiety and sleep drugs like benzodiazepines
 * Use of or withdrawal from pain-relievers such as opioids
 * Heart disease
 * Restless legs syndrome, which can cause sleep onset insomnia due to the discomforting sensations felt and the need to move the legs or other body parts to relieve these sensations
 * Periodic limb movement disorder (PLMD), which occurs during sleep and can cause arousals of which the sleeper is unaware
 * Pain: an injury or condition that causes pain can preclude an individual from finding a comfortable position in which to fall asleep, and can also cause awakening.
 * Hormone shifts such as those that precede menstruation and those during menopause
 * Life events such as fear, stress, anxiety, emotional or mental tension, work problems, financial stress, birth of a child, and bereavement
 * Gastrointestinal issues such as heartburn or constipation
 * Mental, neurobehavioral, or neurodevelopmental disorders such as bipolar disorder, clinical depression, generalized anxiety disorder, post traumatic stress disorder, schizophrenia, obsessive compulsive disorder, autism, dementia, ADHD, and FASD
 * Disturbances of the circadian rhythm, such as shift work and jet lag, can cause an inability to sleep at some times of the day and excessive sleepiness at other times of the day. Chronic circadian rhythm disorders are characterized by similar symptoms.
 * Certain neurological disorders such as brain lesions, or a history of traumatic brain injury
 * Medical conditions such as hyperthyroidism
 * Abuse of over-the-counter or prescription sleep aids (sedative or depressant drugs) can produce rebound insomnia
 * Poor sleep hygiene, e.g., noise or over-consumption of caffeine
 * A rare genetic condition can cause a prion-based, permanent and eventually fatal form of insomnia called fatal familial insomnia
 * Physical exercise: exercise-induced insomnia is common in athletes in the form of prolonged sleep onset latency
 * Increased exposure to the blue light from artificial sources, such as phones or computers
 * Chronic pain
 * Lower back pain
 * Asthma

Sleep studies using polysomnography have suggested that people who have sleep disruption have elevated night-time levels of circulating cortisol and adrenocorticotropic hormone. They also have an elevated metabolic rate, which does not occur in people who do not have insomnia but whose sleep is intentionally disrupted during a sleep study. Studies of brain metabolism using positron emission tomography (PET) scans indicate that people with insomnia have higher metabolic rates by night and by day. The question remains whether these changes are the causes or consequences of long-term insomnia.

Genetics
Heritability estimates of insomnia vary between 38% in males to 59% in females. A genome-wide association study (GWAS) identified 3 genomic loci and 7 genes that influence the risk of insomnia, and showed that insomnia is highly polygenic. In particular, a strong positive association was observed for the MEIS1 gene in both males and females. This study showed that the genetic architecture of insomnia strongly overlaps with psychiatric disorders and metabolic traits.

It has been hypothesized that epigenetics might also influence insomnia through a controlling process of both sleep regulation and brain-stress response having an impact as well on the brain plasticity.

Alcohol-induced
Alcohol is often used as a form of self-treatment of insomnia to induce sleep. However, alcohol use to induce sleep can be a cause of insomnia. Long-term use of alcohol is associated with a decrease in NREM stage 3 and 4 sleep as well as suppression of REM sleep and REM sleep fragmentation. Frequent moving between sleep stages occurs with; awakenings due to headaches, the need to urinate, dehydration, and excessive sweating. Glutamine rebound also plays a role as when someone is drinking; alcohol inhibits glutamine, one of the body's natural stimulants. When the person stops drinking, the body tries to make up for lost time by producing more glutamine than it needs. The increase in glutamine levels stimulates the brain while the drinker is trying to sleep, keeping them from reaching the deepest levels of sleep. Stopping chronic alcohol use can also lead to severe insomnia with vivid dreams. During withdrawal, REM sleep is typically exaggerated as part of a rebound effect.

Benzodiazepine-induced
Like alcohol, benzodiazepines, such as alprazolam, clonazepam, lorazepam, and diazepam, are commonly used to treat insomnia in the short-term (both prescribed and self-medicated), but worsen sleep in the long-term. While benzodiazepines can put people to sleep (i.e., inhibit NREM stage 1 and 2 sleep), while asleep, the drugs disrupt sleep architecture: decreasing sleep time, delaying time to REM sleep, and decreasing deep slow-wave sleep (the most restorative part of sleep for both energy and mood).

Opioid-induced
Opioid medications such as hydrocodone, oxycodone, and morphine are used for insomnia that is associated with pain due to their analgesic properties and hypnotic effects. Opioids can fragment sleep and decrease REM and stage 2 sleep. By producing analgesia and sedation, opioids may be appropriate in carefully selected patients with pain-associated insomnia. However, dependence on opioids can lead to long-term sleep disturbances.

Risk factors
Insomnia affects people of all age groups but people in the following groups have a higher chance of acquiring insomnia:
 * Individuals older than 60
 * History of mental health disorder including depression, etc.
 * Emotional stress
 * Working late night shifts
 * Traveling through different time zones
 * Having chronic diseases such as diabetes, kidney disease, lung disease, Alzheimer's, or heart disease
 * Alcohol or drug use disorders
 * Gastrointestinal reflux disease
 * Heavy smoking
 * Work stress
 * Individuals of low SES
 * Urban Neighborhoods
 * Household stress

Mechanism
Two main models exists as to the mechanism of insomnia, cognitive and physiological. The cognitive model suggests rumination and hyperarousal contribute to preventing a person from falling asleep and might lead to an episode of insomnia.

The physiological model is based upon three major findings in people with insomnia; firstly, increased urinary cortisol and catecholamines have been found suggesting increased activity of the HPA axis and arousal; second, increased global cerebral glucose utilization during wakefulness and NREM sleep in people with insomnia; and lastly, increased full body metabolism and heart rate in those with insomnia. All these findings taken together suggest a deregulation of the arousal system, cognitive system, and HPA axis all contributing to insomnia. However, it is unknown if the hyperarousal is a result of, or cause of insomnia. Altered levels of the inhibitory neurotransmitter GABA have been found, but the results have been inconsistent, and the implications of altered levels of such a ubiquitous neurotransmitter are unknown. Studies on whether insomnia is driven by circadian control over sleep or a wake dependent process have shown inconsistent results, but some literature suggests a deregulation of the circadian rhythm based on core temperature. Increased beta activity and decreased delta wave activity has been observed on electroencephalograms; however, the implication of this is unknown.

Around half of post-menopausal women experience sleep disturbances, and generally sleep disturbance is about twice as common in women as men; this appears to be due in part, but not completely, to changes in hormone levels, especially in and post-menopause.

Changes in sex hormones in both men and women as they age may account in part for increased prevalence of sleep disorders in older people.

Diagnosis
In medicine, insomnia is widely measured using the Athens insomnia scale. It is measured using eight different parameters related to sleep, finally represented as an overall scale which assesses an individual's sleep pattern.

A qualified sleep specialist should be consulted for the diagnosis of any sleep disorder so the appropriate measures can be taken. Past medical history and a physical examination need to be done to eliminate other conditions that could be the cause of insomnia. After all other conditions are ruled out a comprehensive sleep history should be taken. The sleep history should include sleep habits, medications (prescription and non-prescription), alcohol consumption, nicotine and caffeine intake, co-morbid illnesses, and sleep environment. A sleep diary can be used to keep track of the individual's sleep patterns. The diary should include time to bed, total sleep time, time to sleep onset, number of awakenings, use of medications, time of awakening, and subjective feelings in the morning. The sleep diary can be replaced or validated by the use of out-patient actigraphy for a week or more, using a non-invasive device that measures movement.

Workers who complain of insomnia should not routinely have polysomnography to screen for sleep disorders. This test may be indicated for patients with symptoms in addition to insomnia, including sleep apnea, obesity, a thick neck diameter, or high-risk fullness of the flesh in the oropharynx. Usually, the test is not needed to make a diagnosis, and insomnia especially for working people can often be treated by changing a job schedule to make time for sufficient sleep and by improving sleep hygiene.

Some patients may need to do an overnight sleep study to determine if insomnia is present. Such a study will commonly involve assessment tools including a polysomnogram and the multiple sleep latency test. Specialists in sleep medicine are qualified to diagnose disorders within the, according to the ICSD, 81 major sleep disorder diagnostic categories. Patients with some disorders, including delayed sleep phase disorder, are often mis-diagnosed with primary insomnia; when a person has trouble getting to sleep and awakening at desired times, but has a normal sleep pattern once asleep, a circadian rhythm disorder is a likely cause.

In many cases, insomnia is co-morbid with another disease, side-effects from medications, or a psychological problem. Approximately half of all diagnosed insomnia is related to psychiatric disorders. For those who have depression, "insomnia should be regarded as a co-morbid condition, rather than as a secondary one;" insomnia typically predates psychiatric symptoms. "In fact, it is possible that insomnia represents a significant risk for the development of a subsequent psychiatric disorder." Insomnia occurs in between 60% and 80% of people with depression. This may partly be due to treatment used for depression.

Determination of causation is not necessary for a diagnosis.

DSM-5 criteria
The DSM-5 criteria for insomnia include the following:

Predominant complaint of dissatisfaction with sleep quantity or quality, associated with one (or more) of the following symptoms: In addition:
 * Difficulty initiating sleep. (In children, this may manifest as difficulty initiating sleep without caregiver intervention.)
 * Difficulty maintaining sleep, characterized by frequent awakenings or problems returning to sleep after awakenings. (In children, this may manifest as difficulty returning to sleep without caregiver intervention.)
 * Early-morning awakening with inability to return to sleep.
 * The sleep disturbance causes clinically significant distress or impairment in social, occupational, educational, academic, behavioral, or other important areas of functioning.
 * The sleep difficulty occurs at least three nights per week.
 * The sleep difficulty is present for at least three months.
 * The sleep difficulty occurs despite adequate opportunity for sleep.
 * The insomnia is not better explained by and does not occur exclusively during the course of another sleep-wake disorder (e.g., narcolepsy, a breathing-related sleep disorder, a circadian rhythm sleep-wake disorder, a parasomnia).
 * The insomnia is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication).

The DSM-IV TR includes insomnia but does not fully elaborate on the symptoms compared to the DSM-5. Instead of early-morning waking as a symptom, the DSM-IV-TR listed “nonrestorative sleep” as a primary symptom. The duration of the experience was also vague in the DSM-IV-TR. The DSM-IV-TR stated that symptoms had to be present for a month, whereas in the DSM-5 it stated symptoms had to be present for three months and occur at least 3 nights a week (Gillette).

Types
Insomnia can be classified as transient, acute, or chronic.
 * Transient insomnia lasts for less than a week. It can be caused by another disorder, by changes in the sleep environment, by the timing of sleep, severe depression, or by stress. Its consequences – sleepiness and impaired psychomotor performance – are similar to those of sleep deprivation.
 * Acute insomnia is the inability to consistently sleep well for a period of less than a month. Insomnia is present when there is difficulty initiating or maintaining sleep or when the sleep that is obtained is non-refreshing or of poor quality. These problems occur despite adequate opportunity and circumstances for sleep and they must result in problems with daytime function. Hyperarousal can be linked to acute insomnia since it activates the body's fight-or-flight response. When we encounter stress or danger, our bodies naturally become more alert, which can interfere with our capacity to both fall asleep and remain asleep. This heightened state of arousal can be useful in the short term during threatening situations, but if it continues over an extended period, it can result in acute insomnia. Acute insomnia is also known as short term insomnia or stress related insomnia.
 * Chronic insomnia lasts for longer than a month. It can be caused by another disorder, or it can be a primary disorder. Common causes of chronic insomnia include persistent stress, trauma, work schedules, poor sleep habits, medications, and other mental health disorders. When an individual consistently engages in behaviors that disrupt their sleep, such as irregular sleep schedules, spending excessive time awake in bed, or engaging in stimulating activities close to bedtime, it can lead to conditioned wakefulness contributing to chronic insomnia. People with high levels of stress hormones or shifts in the levels of cytokines are more likely than others to have chronic insomnia. Its effects can vary according to its causes. They might include muscular weariness, hallucinations, and/or mental fatigue.

Prevention
Prevention and treatment of insomnia may require a combination of cognitive behavioral therapy, medications, and lifestyle changes.

Among lifestyle practices, going to sleep and waking up at the same time each day can create a steady pattern which may help to prevent insomnia. Avoidance of vigorous exercise and caffeinated drinks a few hours before going to sleep is recommended, while exercise earlier in the day may be beneficial. Other practices to improve sleep hygiene may include:

 * Avoiding or limiting naps
 * Treating pain at bedtime
 * Avoiding large meals, beverages, alcohol, and nicotine before bedtime
 * Finding soothing ways to relax into sleep, including use of white noise
 * Making the bedroom suitable for sleep by keeping it dark, cool, and free of devices, such as clocks, cell phones, or televisions
 * Maintain regular exercise
 * Try relaxing activities before sleeping

Management
It is recommended to rule out medical and psychological causes before deciding on the treatment for insomnia. Cognitive behavioral therapy is generally the first line treatment once this has been done. It has been found to be effective for chronic insomnia. The beneficial effects, in contrast to those produced by medications, may last well beyond the stopping of therapy.

Medications have been used mainly to reduce symptoms in insomnia of short duration; their role in the management of chronic insomnia remains unclear. Several different types of medications may be used. Many doctors do not recommend relying on prescription sleeping pills for long-term use. It is also important to identify and treat other medical conditions that may be contributing to insomnia, such as depression, breathing problems, and chronic pain. As of 2022, many people with insomnia were reported as not receiving overall sufficient sleep or treatment for insomnia.

Non-medication based
Non-medication based strategies have comparable efficacy to hypnotic medication for insomnia and they may have longer lasting effects. Hypnotic medication is only recommended for short-term use because dependence with rebound withdrawal effects upon discontinuation or tolerance can develop.

Non medication based strategies provide long lasting improvements to insomnia and are recommended as a first line and long-term strategy of management. Behavioral sleep medicine (BSM) tries to address insomnia with non-pharmacological treatments. The BSM strategies used to address chronic insomnia include attention to sleep hygiene, stimulus control, behavioral interventions, sleep-restriction therapy, paradoxical intention, patient education, and relaxation therapy. Some examples are keeping a journal, restricting the time spent awake in bed, practicing relaxation techniques, and maintaining a regular sleep schedule and a wake-up time. Behavioral therapy can assist a patient in developing new sleep behaviors to improve sleep quality and consolidation. Behavioral therapy may include, learning healthy sleep habits to promote sleep relaxation, undergoing light therapy to help with worry-reduction strategies and regulating the circadian clock.

Music may improve insomnia in adults (see music and sleep). EEG biofeedback has demonstrated effectiveness in the treatment of insomnia with improvements in duration as well as quality of sleep. Self-help therapy (defined as a psychological therapy that can be worked through on one's own) may improve sleep quality for adults with insomnia to a small or moderate degree.

Stimulus control therapy is a treatment for patients who have conditioned themselves to associate the bed, or sleep in general, with a negative response. As stimulus control therapy involves taking steps to control the sleep environment, it is sometimes referred interchangeably with the concept of sleep hygiene. Examples of such environmental modifications include using the bed for sleep and sex only, not for activities such as reading or watching television; waking up at the same time every morning, including on weekends; going to bed only when sleepy and when there is a high likelihood that sleep will occur; leaving the bed and beginning an activity in another location if sleep does not occur in a reasonably brief period of time after getting into bed (commonly ~20 min); reducing the subjective effort and energy expended trying to fall asleep; avoiding exposure to bright light during night-time hours, and eliminating daytime naps.

A component of stimulus control therapy is sleep restriction, a technique that aims to match the time spent in bed with actual time spent asleep. This technique involves maintaining a strict sleep-wake schedule, sleeping only at certain times of the day and for specific amounts of time to induce mild sleep deprivation. Complete treatment usually lasts up to 3 weeks and involves making oneself sleep for only a minimum amount of time that they are actually capable of on average, and then, if capable (i.e. when sleep efficiency improves), slowly increasing this amount (~15 min) by going to bed earlier as the body attempts to reset its internal sleep clock. Bright light therapy may be effective for insomnia.

Paradoxical intention is a cognitive reframing technique where the insomniac, instead of attempting to fall asleep at night, makes every effort to stay awake (i.e. essentially stops trying to fall asleep). One theory that may explain the effectiveness of this method is that by not voluntarily making oneself go to sleep, it relieves the performance anxiety that arises from the need or requirement to fall asleep, which is meant to be a passive act. This technique has been shown to reduce sleep effort and performance anxiety and also lower subjective assessment of sleep-onset latency and overestimation of the sleep deficit (a quality found in many insomniacs).

Sleep hygiene
Sleep hygiene is a common term for all of the behaviors which relate to the promotion of good sleep. They include habits which provide a good foundation for sleep and help to prevent insomnia. However, sleep hygiene alone may not be adequate to address chronic insomnia. Sleep hygiene recommendations are typically included as one component of cognitive behavioral therapy for insomnia (CBT-I). Recommendations include reducing caffeine, nicotine, and alcohol consumption, maximizing the regularity and efficiency of sleep episodes, minimizing medication usage and daytime napping, the promotion of regular exercise, and the facilitation of a positive sleep environment. The creation of a positive sleep environment may also be helpful in reducing the symptoms of insomnia. On the other hand, a systematic review by the AASM concluded that clinicians should not prescribe sleep hygiene for insomnia due to the evidence of absence of its efficacy and potential delaying of adequate treatment, recommending instead that effective therapies such as CBT-i should be preferred.

Cognitive behavioral therapy
There is some evidence that cognitive behavioral therapy for insomnia (CBT-I) is superior in the long-term to benzodiazepines and the nonbenzodiazepines in the treatment and management of insomnia. In this therapy, patients are taught improved sleep habits and relieved of counter-productive assumptions about sleep. Common misconceptions and expectations that can be modified include:
 * Unrealistic sleep expectations.
 * Misconceptions about insomnia causes.
 * Amplifying the consequences of insomnia.
 * Performance anxiety after trying for so long to have a good night's sleep by controlling the sleep process.

Numerous studies have reported positive outcomes of combining cognitive behavioral therapy for insomnia treatment with treatments such as stimulus control and the relaxation therapies. Hypnotic medications are equally effective in the short-term treatment of insomnia, but their effects wear off over time due to tolerance. The effects of CBT-I have sustained and lasting effects on treating insomnia long after therapy has been discontinued. The addition of hypnotic medications with CBT-I adds no benefit in insomnia. The long lasting benefits of a course of CBT-I shows superiority over pharmacological hypnotic drugs. Even in the short term when compared to short-term hypnotic medication such as zolpidem, CBT-I still shows significant superiority. Thus CBT-I is recommended as a first line treatment for insomnia.

Common forms of CBT-I treatments include stimulus control therapy, sleep restriction, sleep hygiene, improved sleeping environments, relaxation training, paradoxical intention, and biofeedback.

CBT is the well-accepted form of therapy for insomnia since it has no known adverse effects, whereas taking medications to alleviate insomnia symptoms have been shown to have adverse side effects. Nevertheless, the downside of CBT is that it may take a lot of time and motivation.

Acceptance and commitment therapy
Treatments based on the principles of acceptance and commitment therapy (ACT) and metacognition have emerged as alternative approaches to treating insomnia. ACT rejects the idea that behavioral changes can help insomniacs achieve better sleep, since they require "sleep efforts" - actions which create more "struggle" and arouse the nervous system, leading to hyperarousal. The ACT approach posits that acceptance of the negative feelings associated with insomnia can, in time, create the right conditions for sleep. Mindfulness practice is a key feature of this approach, although mindfulness is not practised to induce sleep (this in itself is a sleep effort to be avoided) but rather as a longer-term activity to help calm the nervous system and create the internal conditions from which sleep can emerge.

A key distinction between CBT-i and ACT lies in the divergent approaches to time spent awake in bed. Proponents of CBT-i advocate minimizing time spent awake in bed, on the basis that this creates cognitive association between being in bed and wakefulness. The ACT approach proposes that avoiding time in bed may increase the pressure to sleep and arouse the nervous system further.

Research has shown that "ACT has a significant effect on primary and comorbid insomnia and sleep quality, and ... can be used as an appropriate treatment method to control and improve insomnia".

Internet interventions
Despite the therapeutic effectiveness and proven success of CBT, treatment availability is significantly limited by a lack of trained clinicians, poor geographical distribution of knowledgeable professionals, and expense. One way to potentially overcome these barriers is to use the Internet to deliver treatment, making this effective intervention more accessible and less costly. The Internet has already become a critical source of health-care and medical information. Although the vast majority of health websites provide general information, there is growing research literature on the development and evaluation of Internet interventions.

These online programs are typically behaviorally-based treatments that have been operationalized and transformed for delivery via the Internet. They are usually highly structured; automated or human supported; based on effective face-to-face treatment; personalized to the user; interactive; enhanced by graphics, animations, audio, and possibly video; and tailored to provide follow-up and feedback.

There is good evidence for the use of computer based CBT for insomnia.

Medications
Many people with insomnia use sleeping tablets and other sedatives. In some places medications are prescribed in over 95% of cases. They, however, are a second line treatment. In 2019, the US Food and Drug Administration stated it is going to require warnings for eszopiclone, zaleplon, and zolpidem, due to concerns about serious injuries resulting from abnormal sleep behaviors, including sleepwalking or driving a vehicle while asleep.

The percentage of adults using a prescription sleep aid increases with age. During 2005–2010, about 4% of U.S. adults aged 20 and over reported that they took prescription sleep aids in the past 30 days. Rates of use were lowest among the youngest age group (those aged 20–39) at about 2%, increased to 6% among those aged 50–59, and reached 7% among those aged 80 and over. More adult women (5%) reported using prescription sleep aids than adult men (3%). Non-Hispanic white adults reported higher use of sleep aids (5%) than non-Hispanic black (3%) and Mexican-American (2%) adults. No difference was shown between non-Hispanic black adults and Mexican-American adults in use of prescription sleep aids.

Antihistamines
As an alternative to taking prescription drugs, some evidence shows that an average person seeking short-term help may find relief by taking over-the-counter antihistamines such as diphenhydramine or doxylamine. Diphenhydramine and doxylamine are widely used in nonprescription sleep aids. They are the most effective over-the-counter sedatives currently available, at least in much of Europe, Canada, Australia, and the United States, and are more sedating than some prescription hypnotics. Antihistamine effectiveness for sleep may decrease over time, and anticholinergic side-effects (such as dry mouth) may also be a drawback with these particular drugs. While addiction does not seem to be an issue with this class of drugs, they can induce dependence and rebound effects upon abrupt cessation of use. However, people whose insomnia is caused by restless legs syndrome may have worsened symptoms with antihistamines.

Antidepressants
While insomnia is a common symptom of depression, antidepressants are effective for treating sleep problems whether or not they are associated with depression. While all antidepressants help regulate sleep, some antidepressants, such as amitriptyline, doxepin, mirtazapine, trazodone, and trimipramine, can have an immediate sedative effect, and are prescribed to treat insomnia. Trazodone was at the beginning of the 2020s the biggest prescribed drug for sleep in the United States despite not being indicated for sleep.

Amitriptyline, doxepin, and trimipramine all have antihistaminergic, anticholinergic, antiadrenergic, and antiserotonergic properties, which contribute to both their therapeutic effects and side effect profiles, while mirtazapine's actions are primarily antihistaminergic and antiserotonergic and trazodone's effects are primarily antiadrenergic and antiserotonergic. Mirtazapine is known to decrease sleep latency (i.e., the time it takes to fall asleep), promoting sleep efficiency and increasing the total amount of sleeping time in people with both depression and insomnia.

Agomelatine, a melatonergic antidepressant with claimed sleep-improving qualities that does not cause daytime drowsiness, is approved for the treatment of depression though not sleep conditions in the European Union and Australia. After trials in the United States, its development for use there was discontinued in October 2011 by Novartis, who had bought the rights to market it there from the European pharmaceutical company Servier.

A 2018 Cochrane review found the safety of taking antidepressants for insomnia to be uncertain with no evidence supporting long term use.

Melatonin agonists
Melatonin receptor agonists such as melatonin and ramelteon are used in the treatment of insomnia. The evidence for melatonin in treating insomnia is generally poor. There is low-quality evidence that it may speed the onset of sleep by 6minutes. Ramelteon does not appear to speed the onset of sleep or the amount of sleep a person gets.

Usage of melatonin as a treatment for insomnia in adults has increased from 0.4% between 1999 and 2000 to nearly 2.1% between 2017 and 2018.

While the use of melatonin in the short-term has been proven to be generally safe and it is shown to not be a dependent medication, side effects can still occur.

Most common side effects of melatonin include:

 * Headache
 * Dizziness
 * Nausea
 * Daytime drowsiness

Prolonged-release melatonin may improve quality of sleep in older people with minimal side effects.

Studies have also shown that children who are on the autism spectrum or have learning disabilities, attention-deficit hyperactivity disorder (ADHD) or related neurological diseases can benefit from the use of melatonin. This is because they often have trouble sleeping due to their disorders. For example, children with ADHD tend to have trouble falling asleep because of their hyperactivity and, as a result, tend to be tired during most of the day. Another cause of insomnia in children with ADHD is the use of stimulants used to treat their disorder. Children who have ADHD then, as well as the other disorders mentioned, may be given melatonin before bedtime in order to help them sleep.

Benzodiazepines

The most commonly used class of hypnotics for insomnia are the benzodiazepines. Benzodiazepines are not significantly better for insomnia than antidepressants. Chronic users of hypnotic medications for insomnia do not have better sleep than chronic insomniacs not taking medications. In fact, chronic users of hypnotic medications have more regular night-time awakenings than insomniacs not taking hypnotic medications. Many have concluded that these drugs cause an unjustifiable risk to the individual and to public health and lack evidence of long-term effectiveness. It is preferred that hypnotics be prescribed for only a few days at the lowest effective dose and avoided altogether wherever possible, especially in the elderly. Between 1993 and 2010, the prescribing of benzodiazepines to individuals with sleep disorders has decreased from 24% to 11% in the US, coinciding with the first release of nonbenzodiazepines.

The benzodiazepine and nonbenzodiazepine hypnotic medications also have a number of side-effects such as day time fatigue, motor vehicle crashes and other accidents, cognitive impairments, and falls and fractures. Elderly people are more sensitive to these side-effects. Some benzodiazepines have demonstrated effectiveness in sleep maintenance in the short term but in the longer term benzodiazepines can lead to tolerance, physical dependence, benzodiazepine withdrawal syndrome upon discontinuation, and long-term worsening of sleep, especially after consistent usage over long periods of time. Benzodiazepines, while inducing unconsciousness, actually worsen sleep as – like alcohol – they promote light sleep while decreasing time spent in deep sleep. A further problem is, with regular use of short-acting sleep aids for insomnia, daytime rebound anxiety can emerge. Although there is little evidence for benefit of benzodiazepines in insomnia compared to other treatments and evidence of major harm, prescriptions have continued to increase. This is likely due to their addictive nature, both due to misuse and because – through their rapid action, tolerance and withdrawal they can "trick" insomniacs into thinking they are helping with sleep. There is a general awareness that long-term use of benzodiazepines for insomnia in most people is inappropriate and that a gradual withdrawal is usually beneficial due to the adverse effects associated with the long-term use of benzodiazepines and is recommended whenever possible.

Benzodiazepines all bind unselectively to the GABAA receptor. Some theorize that certain benzodiazepines (hypnotic benzodiazepines) have significantly higher activity at the α1 subunit of the GABAA receptor compared to other benzodiazepines (for example, triazolam and temazepam have significantly higher activity at the α1 subunit compared to alprazolam and diazepam, making them superior sedative-hypnotics – alprazolam and diazepam, in turn, have higher activity at the α2 subunit compared to triazolam and temazepam, making them superior anxiolytic agents). Modulation of the α1 subunit is associated with sedation, motor impairment, respiratory depression, amnesia, ataxia, and reinforcing behavior (drug-seeking behavior). Modulation of the α2 subunit is associated with anxiolytic activity and disinhibition. For this reason, certain benzodiazepines may be better suited to treat insomnia than others.

Z-Drugs
Nonbenzodiazepine or Z-drug sedative–hypnotic drugs, such as zolpidem, zaleplon, zopiclone, and eszopiclone, are a class of hypnotic medications that are similar to benzodiazepines in their mechanism of action, and indicated for mild to moderate insomnia. Their effectiveness at improving time to sleeping is slight, and they have similar—though potentially less severe—side effect profiles compared to benzodiazepines. Prescribing of nonbenzodiazepines has seen a general increase since their initial release on the US market in 1992, from 2.3% in 1993 among individuals with sleep disorders to 13.7% in 2010.

Orexin antagonists
Orexin receptor antagonists are a more recently introduced class of sleep medications and include suvorexant, lemborexant, and daridorexant, all of which are FDA-approved for treatment of insomnia characterized by difficulties with sleep onset and/or sleep maintenance. They are oriented towards blocking signals in the brain that stimulate wakefulness, therefore claiming to address insomnia without creating dependence. There are three dual orexin receptor (DORA) drugs on the market: Belsomra (Merck), Dayvigo (Eisai) and Quviviq (Idorsia).

Antipsychotics
Certain atypical antipsychotics, particularly quetiapine, olanzapine, and risperidone, are used in the treatment of insomnia. However, while common, use of antipsychotics for this indication is not recommended as the evidence does not demonstrate a benefit, and the risk of adverse effects are significant. A major 2022 systematic review and network meta-analysis of medications for insomnia in adults found that quetiapine did not demonstrate any short-term benefits for insomnia. Some of the more serious adverse effects may also occur at the low doses used, such as dyslipidemia and neutropenia. Such concerns of risks at low doses are supported by Danish observational studies that showed an association of use of low-dose quetiapine (excluding prescriptions filled for tablet strengths >50 mg) with an increased risk of major cardiovascular events as compared to use of Z-drugs, with most of the risk being driven by cardiovascular death. Laboratory data from an unpublished analysis of the same cohort also support the lack of dose-dependency of metabolic side effects, as new use of low-dose quetiapine was associated with a risk of increased fasting triglycerides at one-year follow-up. Concerns regarding side effects are greater in the elderly.

Other sedatives
Gabapentinoids like gabapentin and pregabalin have sleep-promoting effects but are not commonly used for treatment of insomnia. Gabapentin is not effective in helping alcohol related insomnia.

Barbiturates, while once used, are no longer recommended for insomnia due to the risk of addiction and other side effects.

Comparative effectiveness
Medications for the treatment of insomnia have a wide range of effect sizes. When comparing drugs such as benzodiazepines, Z-drugs, sedative antidepressants and antihistamines, quetiapine, orexin receptor antagonists, and melatonin receptor agonists, the orexin antagonist lemborexant and the Z-drug eszopiclone had the best profiles overall in terms of efficacy, tolerability, and acceptability.

Alternative medicine
Herbal products, such as valerian, kava, chamomile, and lavender, have been used to treat insomnia. However, there is no quality evidence that they are effective and safe. The same is true for cannabis and cannabinoids. It is likewise unclear whether acupuncture is useful in the treatment of insomnia.

Prognosis

A survey of 1.1 million residents in the United States found that those that reported sleeping about 7 hours per night had the lowest rates of mortality, whereas those that slept for fewer than 6 hours or more than 8 hours had higher mortality rates. Severe insomnia – sleeping less than 3.5 hours in women and 4.5 hours in men – is associated with a 15% increase in mortality, while getting 8.5 or more hours of sleep per night was associated with a 15% higher mortality rate.

With this technique, it is difficult to distinguish lack of sleep caused by a disorder which is also a cause of premature death, versus a disorder which causes a lack of sleep, and the lack of sleep causing premature death. Most of the increase in mortality from severe insomnia was discounted after controlling for associated disorders. After controlling for sleep duration and insomnia, use of sleeping pills was also found to be associated with an increased mortality rate.

The lowest mortality was seen in individuals who slept between six and a half and seven and a half hours per night. Even sleeping only 4.5 hours per night is associated with very little increase in mortality. Thus, mild to moderate insomnia for most people is associated with increased longevity and severe insomnia is associated only with a very small effect on mortality. It is unclear why sleeping longer than 7.5 hours is associated with excess mortality.

Epidemiology
Between 10% and 30% of adults have insomnia at any given point in time and up to half of people have insomnia in a given year, making it the most common sleep disorder. About 6% of people have insomnia that is not due to another problem and lasts for more than a month. People over the age of 65 are affected more often than younger people. Females are more often affected than males. Insomnia is 40% more common in women than in men.

There are higher rates of insomnia reported among university students compared to the general population.

Society and culture
The word insomnia is from in + somnus "without sleep" and -ia as a nominalizing suffix.

The popular press have published stories about people who supposedly never sleep, such as that of Thái Ngọc and Al Herpin. Horne writes "everybody sleeps and needs to do so", and generally this appears true. However, he also relates from contemporary accounts the case of Paul Kern, who was shot in 1915 fighting in World War I and then "never slept again" until his death in 1955. Kern appears to be a completely isolated, unique case.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Insomnia


text:
Y-wing

The Koensayr BTL Y-wing assault starfighter/bomber are a series of fictional spacecraft from the Star Wars franchise. They are depicted as the star fighters of the Galactic Republic (BTL-B, fully paneled & early/stock version of the Y-wing), Rebel Alliance (BTL-A4, the stripped-down and heavily modified version of the former Republic BTL-B Clone Wars Y-wing), New Republic (used Rebel Y-wings and later a new version called the BTA-NR2), and the BTA-NR2 Y-wing which served the Resistance. Y-wings are known for being ideally suited for anti-shipping, close air support, air interdiction, force protection and ground attack missions. Y-wing made their theatrical appearance in Star Wars Episode IV: A New Hope and have featured in movies, television shows, and the Star Wars expanded universe's books, comics, and games.

Origin and design
Colin Cantwell, who also designed the saga's TIE fighters, initially designed the Y-wing with a large bubble turret for a gunner. However, the dome did not appear properly when filmed against bluescreen and subsequent designs omitted the turret.

Appearances
In the original Star Wars movie (1977), a group of Y-wings designated "Gold Squadron" took part in the attack on the Death Star. Led by squadron leader Jon Vander (Angus MacInnes), Y-wings made the first unsuccessful "trench run" on the Death Star's exhaust port, and only one Y-wing would survive the battle itself. (The pilot of the surviving Y-Wing differs between Canon and Legends). Luke Skywalker pilots a Y-wing in the animated segment of the 1978 Star Wars Holiday Special. Y-wings made a brief appearance at the end of The Empire Strikes Back (1980) when the heroes are reunited with the Rebel fleet, and feature alongside other Rebel starfighters during the climatic space battle of Return of the Jedi (1983). Y-wings were later seen in The Clone Wars 2008 television series as their stock & early version. Here they are depicted as fighter-bombers used by the Galactic Republic in the Clone Wars against the Separatists. General Anakin Skywalker is shown leading a squadron of Y-wings on one of their first missions to take out a Separatist cruiser, where they are noted for their powerful shields and secondary gunner. In the Star Wars Rebels 2014 animated series, the crew of the Ghost are shown stealing decommissioned Old Republic Y-wings, in the process of being dismantled by the Galactic Empire, for use by the nascent Rebel Alliance. These former Republic Y-wings the Rebellion had captured and reclaimed from scrap had become skeletal by having their armor paneling & hull stripped-down and they were heavily modified to fit rebel specifications to transform the former Republic Y-wings into Rebellion Y-wings. Rebel BTL-A4 Y-wings are stripped down and heavily modified BTL-B Y-wings that were leftover from the Clone Wars. Y-wings made their theatrical reappearance in Rogue One (2016), an anthology film set immediately prior to the events of the original Star Wars film. Here the Y-wings of Gold Squadron are shown playing a pivotal role during the Battle of Scarif in disabling an Imperial Star Destroyer with ion torpedoes. Y-wings would appear again as newer & upgraded models during the climax of Star Wars: The Rise of Skywalker (2019).

Depiction
Based on Star Wars supplemental retail material, the Galactic Republic commissioned Koensayr Manufacturing to produce the BTL-B Y-wing during the early part of the Clone Wars. Prized for its durability and long-range striking capability, the success of the Y-wing prompted further production of the original model and a number of variants. However, when the war concluded and the Galactic Empire came to power, Y-wings were decommissioned and relegated to military surplus sellers or scrapyards. The Rebel Alliance sought to buy or commandeer as many Y-wings as possible and they became the most readily available starfighters to the Rebellion during the Galactic Civil War. Rebel Y-wings were used to perform a variety of missions including courier, escort and reconnaissance. The original Y-wing (The BTL-B) features a forward module seating a pilot in the cockpit and a gunner in a bubble turret. An astromech droid (which served as the fighter's navigation system) fits into a dedicated socket behind them. The module contains the starfighter's armaments: two forward-firing laser cannons, twin ion cannons in the turret, and a pair of torpedo launchers with six-round magazines capable of launching bombs, cluster missiles and other ordnance. The module connects to two powerful ion engines via reinforced central spar and cross wing, all encased in heavy armor plating. Heavily modified and skeletal versions of the Original Y-Wing (BTL-B) include the BTL-S3, which replaces the bubble turret with a remote-controlled turret and seats the gunner behind the pilot in the cockpit, and the BTL-A4, which removes the gunner altogether and gives the pilot control of the ion cannons. Once acquired, Rebel technicians modified the fighter-bombers to make them more suitable to the Rebellion's hit-and-run tactics. Armor plating was removed to save on weight and make it easier to perform maintenance, compensated for by increasing deflector shield power. Various other components were removed or rearranged - such as replacing the six-round torpedo magazines with four-round versions - to lighten weight and increase performance while maintaining overall integrity. The resulting modification makes these Rebel Y-wings faster and more lethal than its original version making the old BTL-B become the new BTL-A4 Y-wing. After the defeat of the Empire, Koensayr introduced a new version of the Y-wing to capitalize on the fighter's popularity. This BTA-NR2 model emulates the look of the Rebel-modified Y-wings both because the public is more familiar with this version and because it allows for greater customization. While outwardly mimicking the "classic" Y-wing design, the new version features various upgrades including stronger shields and more sophisticated sensors.

Cultural impact
In 2018, Star Wars starfighters had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. Of those tested, the Y-wing had a drag coefficient of .68, which, while worse than the real-life example of the F-4E Phantom with a rating of .02, was better than that of most TIE Fighters tested. These poor results were rationalized with the in-universe explanations that drag coefficient plays no role in space travel and that Star Wars fighters can use repulsorlifts and deflector shields to give themselves better flight profiles.

title: Y-wing


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X-wing fighter

The X-wing starfighter is a name applied to a family of fictional spacecraft manufactured by the Incom Corporation and later the Incom-FreiTek Corporation from the Star Wars franchise. Named for the distinctive shape made when its s-foils (wings) are in attack position, the X-wing was a class of starfighter used by the Rebel Alliance in their conflict with the Galactic Empire. It made its theatrical debut, as the T-65B model, in Star Wars (1977) as the spacecraft piloted by Luke Skywalker and the Red Squadron when Luke destroyed the Death Star. The starfighter featured extensively in the Star Wars original trilogy and in the Expanded Universe that followed, and has been merchandised as a variety of toys and models.

Starting with The Force Awakens (2015), a new model of X-wing was introduced, which has gone on to play a prominent role in the Star Wars sequel trilogy. The T-70 X-wing, flown by the Resistance in their fight against the First Order, is depicted as the successor to the T-65. Although described as being an improvement over the original, in the expanded literature this new X-wing is itself considered outdated, having been replaced by the T-85 X-wing in the New Republic's defense fleet. The T-85 X-wing made its first appearance in the TV series Star Wars Resistance (2018).

Origin and design
Colin Cantwell sketched and built models that eventually became the final X-wing fighter in Star Wars. The X-wings were designed to appear more "traditional" than the Empire's TIE fighters. ILM built miniatures in various scales, with wing markings indicating which prop represented which pilot. When ILM fell behind on generating X-wing footage, Star Wars creator/director George Lucas and his editors temporarily used World War II dogfight footage for initial editing cuts. Each X-wing model was built around a hollow core made from surgical tubing, which allowed lighting, cooling, and electrical connectors for the wing motors to be installed and maintained. The cockpit windows were made from faceted glass so that accurate reflections could be filmed. Although the movie's initial script and novelization describe the X-wings as belonging to "Blue squadron", limitations in bluescreen photography led to the markings on the filming models, as well as the fictional squadron affiliation being changed to red.

In addition to miniatures, special effects expert John Stears and his crew made a single, full-size X-wing for scenes in the Rebels' Yavin 4 base hangar; combined with cardboard cutouts and careful editing, the Rebels appear to have dozens of fighters. The production crew also made a full-size X-wing cockpit that was used for all actors; the astromech droid visible behind each actor was changed for each starfighter. Background noise pitch and tone also varied between X-wings to further differentiate the characters piloting them.

The "lake" in which Luke Skywalker (Mark Hamill) crashes his X-wing in The Empire Strikes Back was only 3.5 ft deep, requiring the creation of a rig resembling the starfighter sitting in the lake at an angle. The rig was built in hinged sections so it could be manipulated by frogmen to sink or rise, a key feature for the scene when Luke fails to levitate his ship from the water.

In 1993, ILM visual effects specialist John Knoll created a proof of concept test of dogfighting X-wings and TIE fighters to demonstrate the feasibility of using commercially available desktop computer software for simple animation work. This resulted in numerous parts of space battle scenes being "re-shot" as digital animations for the original trilogy's Special Edition releases. The ARC-170 starfighter seen in Star Wars: Episode III – Revenge of the Sith is the ancestor of the X-wing and is deliberately reminiscent of the X-wing's design.

Depiction
The T-65B X-wing was produced by the Incom Corporation, which had previously supplied the ARC-170 and Z-95 Headhunter starfighters to the Galactic Republic during the Clone Wars. When the Galactic Empire ordered them to produce a new starfighter for the Imperial Navy, Incom engineers took inspiration from their previous work to create the X-wing. Production was already underway however when politicking resulted in the Empire choosing instead to go with Sienar Fleet Systems' TIE fighter. Faced with an overproduction of expensive starfighters, a new market was found when agents of the Rebel Alliance contacted Incom about acquiring their stock of X-wings, to which Incom eagerly agreed. The X-wing quickly became a symbol of the Rebellion thanks to its use in several spectacular victories and the role it played in ultimately defeating the Empire. After the defeat of the Empire, the X-wing starfighters became a staple of the New Republic fleet and later the Resistance, with Incom-FreiTek supplying upgraded T-70 and T-85 models.

Compared to the TIE fighter, the X-wing is said to be slower and less maneuverable in space, but boasts superior firepower, defenses, atmospheric maneuverability, and a supraluminal hyperdrive. Its four laser canons can be fired singly, in pairs or all at once, and each launcher can carry up to three proton torpedoes. In addition to deflector shields, the X-wing possesses a titanium alloy armored hull, electronic countermeasures, and armored cockpit. An inertial dampener protects the pilot from high-g maneuvers, while an anti-gravity "repulsorlift" provides for flight in planetary atmospheres.

The T-65B X-wing's distinctive strike foils or "S-foils" are opened and closed by powerful servo motors in the spacecraft. When in the open or 'attack' position, they provided a greater range of fire to the laser cannons mounted on the end of each wing. They also serve to distribute energy to enlarge the deflector shield, shed waste heat, and function as stabilizer surfaces during air travel.

Instead of a dedicated navigational system, the X-wing makes use of an astromech droid (such as R2-D2) which fits in a socket behind the cockpit. The droid can hold up to 10 hyperspace coordinates, make minor repairs to the craft, and assume full control of the X-wing if needed. As with the pilot's ejection seat, an explosive charge can eject the droid from the X-wing in an emergency.

In Legends
According to roleplaying and other literature prior to Disney's acquisition of Lucasfilm, the origin of the X-wing is somewhat different compared to later material. Incom Corporation had already begun designing the X-wing when the Empire's Imperial Security Bureau began to suspect the company of Rebel sympathies. Before the empire could seize control of the company, the designers defected to the Rebel Alliance and handed over the X-wing's schematics.

The Rebel Alliance adopted the military strategy of Doctrine of Space Denial, wherein the Rebellion would raid Imperial boneyards and shipping frigates, both to disrupt Imperial logistics and operations, and also to requisition desperately needed materials. X-wing hyperdrive capabilities allowed for this kind of harassment and escape before the Empire could react. The presence of a hyperdrive and deflector shields differentiate the X-wing from the Empire's TIE fighters, emphasizing the importance the Rebels place on pilots surviving their missions.

Novels and roleplaying material set after Return of the Jedi showed the X-wing continued to be refined and upgraded in service to the New Republic; the "XJ"-series X-wings, depicted in the war against the Yuuzhan Vong, have a third proton torpedo launcher, stronger lasers and improved engines.

Merchandise and licensing
Kenner Toys produced an X-wing toy as a complement to its action figure line in 1978; this model was made from formed plastic and had a battery-operated light and buzzer in the forward fuselage. The "s-foils" were activated by depressing the molded astromech droid. In 1982, a "battle-damaged" version was released using the same mold but with damage stickers, a grey fuselage, blackened engine inlets, and a darker canopy. In countries outside the U.S., the electronics were removed and the R2-D2 “button” was chrome (apart from the U.S., the electronic X-wing was only available in Brazil, Canada, and France). Kenner also produced a die-cast 1:72 miniature X-wing in 1978 and a smaller scaled version with "battle damage crash feature" for the short lived Micro Collection line in 1982.

The X-wing appeared in four Micro Machines three-packs, including the first Star Wars pack released, a bronzed version, and a pack of three "battle damaged" X-wings with different colored markings. The Micro Machines X-wing has also been released in two single-packs, as a promotional souvenir with German video releases, in a nine-pack of Original Trilogy vehicles, and once in clear plastic. The X-wing appears eight times in the Micro Machines Action Fleet toy line: Luke's starfighter on its own, with "targeter" stand, with Dagobah swamp damage, and in a double pack with a TIE Fighter, Wedge's starfighter on its own, and as a component of the Yavin Rebel Base playset, a toy based on the prototype packaged with Biggs Darklighter's starfighter, and Jek Porkins' starfighter.

Lego also released numerous X-wing models, including a 76-piece miniature X-wing/TIE advanced kit, a 263-piece X-wing (1999/2002), a 563-piece X-wing kit with Yoda's Hut (2004), a 437-piece X-Wing (2006), a 560-piece X-wing (2012), a 730-piece X-wing (2018), and a 474-piece Luke Skywalker's X-wing Fighter (2021). A 1,304-piece "Ultimate Collector's" model was released in 2000. A new "Ultimate Collector's" model with 1,559 pieces was released in 2013. In 2019, the Lego Group's annual Christmas gift to employees was a 1,038-piece Christmas X-wing, which also included Yoda's igloo and a sleigh. In addition to the original T-65 X-wing, Lego has released several models of the newer T-70 X-wing. These include the black/orange Poe's X-wing Fighter (2015), the gray/blue Resistance X-wing Fighter (2016) and orange/white Poe Dameron's X-wing Fighter (2020), as well as several small mini-scale versions.

X-wings also appear in numerous Star Wars games and Expanded Universe stories. The player pilots an X-wing in the Atari Star Wars game. It is also a playable ship in numerous LucasArts games, and is the eponymous vessel in the first of several space combat simulator games. Both the Rebel Assault and Rebel Assault II rail shooters include X-wing levels, and X-wing squadrons are controllable units in the Rebellion and Empire at War strategy games. Decipher and Wizards of the Coast published X-wing and X-wing-related cards for the Star Wars Customizable Card Game and Star Wars Trading Card Game, respectively. Michael A. Stackpole and Aaron Allston wrote the X-wing novel series that focuses on the X-wing pilots of Rogue Squadron and Wraith Squadron, the former expanding the story of pilots like Wedge Antilles who appear in the films. Dark Horse Comics has also published an X-Wing Rogue Squadron series. In 2012, Fantasy Flight Games released the Star Wars: X-Wing Miniatures Game featuring several pilots and variations of the ship. The X-wing also included in its Star Wars: Armada miniatures game and Star Wars: Rebellion board game.

Cultural influence
A model of Luke Skywalker's X-wing was among 250 Star Wars-related items on display at the National Air and Space Museum celebrating the franchise's twentieth anniversary. An original X-wing filming prop sold at auction for $160,000 in July 2016. In 2007, the San Diego Tripoli Rocket Association built and launched a 23 ft X-wing model propelled by four rockets, which disintegrated seconds after liftoff. A life-size X-wing is suspended from the ceiling at the Star Trader gift shop in Disneyland in California, as well as one displayed outdoors by the Star Tours attraction at Disneyland Paris. A life-size X-wing made from Lego blocks appeared in Times Square, and a $3⁄4$-size replica is on display at the Wings Over the Rockies Air & Space Museum in Denver.

In 2018, a number of Star Wars starfighters had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. When tested, the classic T-65 X-wing design had a drag coefficient of 0.45, which is only slightly better than the coefficient of a sphere. The newer T-70 X-wing flown by Poe Dameron (Oscar Isaac) was more aerodynamically sound with a rating of 0.24, but still fell short of the F-4E Phantom with its 0.02 drag coefficient. These poor results were rationalized with the in-universe explanations that drag coefficient plays no role in space travel, and that Star Wars fighters can use repulsorlifts and deflector shields to give themselves better flight profiles.

title: X-wing fighter


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A-wing

Kuat RZ-1 A-wing Interceptor are starfighters in the Star Wars franchise. Designed and manufactured by the Kuat Systems Engineering, they are depicted as fast but fragile interceptors of the Rebel Alliance, conceived for high-speed surgical strikes, deep reconnaissance and escort fighter duty.

A-wings first appear in Return of the Jedi (1983) and later in numerous Star Wars materials and productions. It gained popularity through its depiction in several video games, and since 1985 the A-wing has been merchandised by several companies. They are the fastest vessels in the Star Wars canon, with the advantage of being the smallest hyperspace drive-equipped craft without relying on a carrier, allowing the vessel to extricate itself from a losing battle or escape hostile territory after performing an attack.

Appearances
RZ-1 A-wings from Green Squadron participate in the climactic Battle of Endor depicted in Return of the Jedi (1983). At Endor, an A-wing piloted by Arvel Crynyd (Hilton McRae) crashes into the bridge of the Super Star Destroyer Executor, resulting in the Executor crashing out of control into the second Death Star. In addition to McRae, two women recorded A-wing cockpit footage; one of the actors was cut, and the other was dubbed over by a male actor.

A-wings later appear in various Star Wars Expanded Universe television shows, books, and games. Some Expanded Universe material says Jan Dodonna created the A-wing based on his analysis of the role of speed in the Battle of Yavin, the climactic battle in Star Wars (1977). Later material, such as the Star Wars Rebels television series, depicts the starfighters in use before the events of Star Wars.

The A-wings of Phoenix Squadron play an important role in Rebels' second season (2015–2016). Rebels producers used the A-wing in part because the ship was not used much in Return of the Jedi The fighter's presence in the cartoon was meant to show that different groups used different craft to fight the Empire. The series's episodes "The Holocrons of Fate" and "Twin Suns" also feature the two-seater RZ-1T trainer, a training spacecraft used by the rebels to train recruits. The RZ-1T also appears in the novel Battlefront II: Inferno Squad.

The RZ-1 A-Wing is based on the R-22 A-Wing, also made by Kuat Systems Engineering A later variant, the RZ-2 A-wing, features in Star Wars Battlefront II and in Star Wars: The Last Jedi. It is a bigger spacecraft used by the Resistance against the First Order.

Concept and design
The A-wing was one of two new Rebel Alliance starfighters created for Return of the Jedi. It was dubbed the A fighter because it was the first of the two designs created. Ralph McQuarrie's production paintings of A-wing starfighters were completed after filming and displayed alternative blue markings.

Joe Johnston designed the ship, Wesley Seeds and Lorne Peterson of Industrial Light & Magic built the model, and its pilot figure is based on a World War I German airman. A battle-damaged engine "wing" was snapped into place to represent Arvel Crynyd's damaged fighter as it crashed into the Executor.

McQuarrie's alternative blue-and-white coloring was used for the craft's appearance in Rebels. Photographs from the filming of Star Wars: The Last Jedi show an A-wing on the film set. Screen Rant suggests the A-wing seen in the photographs evokes some of McQuarrie's interpretation of the design, such as the blaster cannon shape and the presence of additional ports in the cockpit.

Depiction
According to Star Wars canon, the A-wing was first produced by Kuat Systems Engineering, which had built the Delta-7 starfighter for the Jedi Order. With the Jedi eradicated (as depicted in Star Wars: Episode III – Revenge of the Sith) and the Delta-7 nearly impossible for non-Jedi to pilot, Kuat designed a new starfighter, the R-22 A-wing, in hopes the Galactic Empire would purchase it. While impressed with prototypes of the R-22, the Empire instead went with the TIE fighter, and forbade Kuat from mass-producing the A-wing. The prototypes were sold to the kingdom of Tammuz-an, which over a decade later were eventually sold to the Rebel Alliance.

Rebel engineers made many alterations to the original R-22 design to produce the RZ-1 model as seen in Return of the Jedi. The original engines were swapped out for more powerful ones, while other major components were replaced with lightweight versions so a supraluminal hyperdrive could be added. The resulting fighter is faster than even the Empire's TIE interceptor and perfect for hit-and-run attacks, long-range patrols, and reconnaissance missions. Its two laser cannons, mounted on special swivel mounts, can elevate or depress 60° vertically; some were modified for full 360° rotation but these had a greater chance to jam. However, engineers could not fit the A-wing with an astromech droid, which limited how many hyperspace coordinates it could carry. The lack of droid assistance also makes it challenging even for a being with Jedi-like reflexes to control a fighter so fast and maneuverable. Consequently, only the best Rebel pilots are allowed to fly the A-wing.

After the Empire was defeated, background material explains how Kuat Systems Engineering made a number of improvements to the design to create the RZ-2 A-wing for the New Republic Defense Fleet. Even faster than the original, the RZ-2 requires less maintenance than the RZ-1, and the swivel mounts that allow its laser cannons to rotate 360° were no longer at risk of jamming. Thanks to the New Republic's disarmament campaign, RZ-2s found their way into the Resistance, which like the Rebellion before allows only the best pilots to fly the A-wing.

Impact
CinemaBlend said the A-wing received little attention after Return of the Jedi because no prominent characters pilot the craft. Kenner in 1985 released an A-wing pilot figure as part of its Power of the Force line, and it released a "magnificent" A-wing toy as part of the Star Wars: Droids line. Since then, the A-wing has been recreated as various other toys, models, and collectibles by companies that include Galoob, Hasbro, Model Products Corporation, Estes Industries, Lego, and Fantasy Flight Games.

Screen Rant said the A-wing gained popularity as a playable craft in the Star Wars: X-Wing space combat simulator (1993), which The Escapist said depicted the ship as "an excellent dogfighter". Subsequent video games that allowed players to pilot the A-wing also contributed to the ship's popularity. Blastr ranked the A-wing 16th on its list of the best Star Wars vehicles.

Prince Harry was photographed sitting in an A-wing cockpit during his and the Duke of Cambridge's April 2016 visit to the Star Wars: Episode VIII set. Responding to the photographs, various publications called the A-wing "iconic", an "unsung hero", "woefully underappreciated", and "a classic".

In 2018 a number of Star Wars starfighters - including the A-wing - had their aerodynamic abilities tested using the Autodesk Flow Design virtual wind tunnel program. Of those starfighters tested the A-wing was among the most aerodynamic designs of all with a drag coefficient of .17, though it was still worse than the real-life example of the F-4E Phantom with a .02 rating. These poor results were rationalized with the in-universe explanations that drag coefficient plays no role in space travel, and that Star Wars fighters can use repulsorlifts and deflector shields to give themselves better flight profiles.

title: A-wing