Suspended animation is the slowing of life processes by external means without termination. Breathing, heartbeat, and other involuntary functions may still occur, but they can only be detected by artificial means. Extreme cold is used to precipitate the slowing of an individual's functions; use of this process has led to the developing science of cryonics. Outside of science fiction, the technique has never been applied to humans for more than a few hours.
Placing astronauts in suspended animation has been proposed as one way for an individual to reach the end of an interplanetary or interstellar journey, avoiding the necessity for a gigantic generation ship; occasionally the two concepts have been combined, with generations of "caretakers" supervising a large population of frozen passengers.
Since the 1970s, hypothermia has been induced for some open-heart surgeries as an alternative to heart-lung machines. Hypothermia, however, only provides a limited amount of time in which to operate and there is a risk of tissue and brain damage for prolonged periods.
While most of the dogs were fine, a few of the revived dogs had severe nervous and movement coordination damage, causing them to be mentally disabled, and demonstrating behavior that was deemed "zombie" like. This has been pushed further by the media which named them "zombie dogs". There is concern that this technique, if used on humans could result in brain damage similar to those suffered by some of the dogs in the experiment.
On January 20, 2006, doctors from the Massachusetts General Hospital in Boston announced they had placed pigs in suspended animation by a similar technique. The pigs were anaesthetised and a major blood loss was induced. After they lost about half their blood the remaining blood was replaced with a chilled saline solution. As the body temperature reached 10 °C the damaged blood vessel was repaired and the blood was returned. The method was tested 200 times with a 90 percent success rate.
On October 9, 2006, the Massachusetts General Hospital in Boston announced they had been able to hibernate mice using the same method. Their heart rate was slowed down from 500 to 200 beats per minute, respiration fell from 120 to 25 breaths per minute and body temperature dropped to 30 °C (natural: 39 °C). After 2 hours of breathing air without hydrogen sulfide the mice returned to normal. Further studies are needed to see if the gas had poisonous effects on the brain.
Experiments on sheep and pigs have been unsuccessful, suggesting that application to large mammals may not be feasible.
There are many research projects currently investigating how to achieve "induced hibernation" in humans. This ability to hibernate humans would be useful for a number of reasons, such as saving the lives of seriously ill or injured people by temporarily putting them in a state of hibernation until treatment can be given. NASA is also interested in possibly putting astronauts in hibernation when going on very long space journeys, making it possible, one day, to visit far-away stars.
There are cases of accidental human hibernation. The most recent is the case of Mitsutaka Uchikoshi, a Japanese man who survived the cold for 24 days in 2006 without food or water when he fell into a hypothermic state similar to hibernation.
Another common use is in space voyages, where the crew is put in hyper-sleep while the ship travels to its destination, saving food and water as well as the crew's lifespans, as in The Twilight Zone episode "The Long Morrow", the films 2001: A Space Odyssey, Alien, and Planet of the Apes and RocketMan, as well as in Buzz's mind in Toy Story. In the Inquisitor War series of novels set in the Warhammer 40,000 universe characters are kept in suspended animation in a stasis chest designed for the long-term storage of food. Their last thoughts as they are suspended remain with them for the entire duration, being either a torture, maddening or a blessing depending on the thought.
This concept can also be seen in the Amusement park ride Mission: SPACE. In the ride, the Astronauts use suspended animation (called "Hypersleep" in the ride) to help them reach Mars. This has two purposes: it increases the believability of the ride, and allows for the ride to be run in a reasonable amount of time.
In the ending of the Delphine Software game Flashback: The Quest for Identity, Conrad finally blows up Titan in order to destroy the morph alien race, but at the cost of having to go into suspended animation as his ship drifts off throughout the cosmos along. In the sequel Fade to Black, he is finally awakened...by the morphs.
Many of the deities of the Cthulhu Mythos, such as the titular Cthulhu himself, are known to be in long impermanent deaths or sleeps which correspond with the modern idea of suspended animation. Equally gazing upon the Great Old One Ghatanothoa is so hideous that anyone who gazes upon it (or even a perfect replica) is petrified into a living mummy. The victim is permanently immobilized--the body taking on the consistency of leather and the internal organs and brain preserved indefinitely--yet remains fully aware.
By the end of the second season of Code Lyoko, Aelita is revealed to have been trapped in Lyoko for about a decade since 1994. Thus, her material form remained in suspended animation until Jeremie Belpois managed to perfect his materialization program.
In the Mortal Kombat: Armageddon , Taven, the hero in Konquest mode, was placed into a sleep spell by his mother, Delia, along with one of his brothers, Daegon. Daegon was revived too early and went mad. When Taven was revived, he learns about his other brother, Rain, and how evil Daegon has gotten.
In the movie Dadasahib, Abu Buckur has hanged but was in suspended animation the whole time, revived later with the help of kind doctors.
In Avatar: The Last Airbender, Aang and Appa survive for a hundred years in suspended animation, having been frozen in an ice bubble under the ocean.
In the SpongeBob SquarePants episode SB-129, Squidward gets stuck in suspended animation for 2000 years when he is locked in the freezer and freezes. Also, Mermaid Man and Barnacle Boy's main enemy, ManRay, is frozen in tartar sauce.
The premise for the television series Red Dwarf involved the main character, Dave Lister, being put in temporal Stasis until he could return to earth for punishment, only to be released 3 million years later when the radiation that killed the crew subsided.
Suspended animation has also been used in many stories (such as the film Demolition Man and the Tekwar novels) as an alternative method of containing incarcerated criminals. The rationale behind this is that prisoners under suspended animation consume less resources (such as food, water, housing and medical care) and that the only significant expense is the maintenance of the suspension units and the security around them. Sometimes, these facilities are placed in space, typically in orbit around Earth. Detractors point out that because there is no sense of the passage of time while in suspended animation, the prisoners do not have to endure the day to day aspects of prison life– thus weakening the punishing effects of prison. Also, there is no opportunity for rehabilitation. Finally, because there is no aging in suspended animation, it has the unfair advantage, in the prisoner's favor, of extending the prisoner's chronological lifespan, thus making life sentences pointless. Demolition Man developed a novel solution to one of these problems in the form of hypnotic rehabilitation, wherein corrective training and socially-beneficial skills are written to the prisoner's brain during their sentence.
In Planetfall, another Infocom game, the player's character escapes to a planet after their ship explodes, and when the player completes the game, it is revealed that the people of that planet have been in suspended animation.
In RocketMan, Fred's crewmates enter "Hypersleep" to pass time while their ship takes 8 months heading to Mars. His roommate, a monkey, steals his hypersleep chamber and leaves him to a miniature monkey-sized one. He curls up in the tiny one, half-closed chamber and falls asleep. Upon waking up, he finds out he only slept a total of thirteen minutes and spends 8 months doing random things to keep himself busy.
In the Alien series, Ripley and her crewmates are placed in Hypersleep capsule. These can keep anything "alive" for up to sixty-five years.
The Hindi film Krrish features a scientist called Rohit Mehra, who was kept in suspended animation by his treacherous colleague Siddhant Arya, so that Rohit's handprint and eye-scan might be used to activate a prescient computer.
In Marvel's Captain America comics, Captain America undergoes suspended animation after being blasted into the North Atlantic by an explosion caused by the accidental triggering of a bomb attached to an experimental drone plane launched by Baron Zemo.
In the British TV Series Hustle, one episode of series 3 entitled Whittaker Our Way Out, a con artist fakes his own death by ingesting a tablet that to all intents and purposes appears to be cyanide, including the characteristic smell of almonds. In fact, it turns out that the capsule has simply induced a form of suspended animation.
In Romeo and Juliet, Juliet takes a potion cooked up by a priest that places her in a death-like state. She uses it to escape her family (unfortunately, it also fools Romeo).
In "The Premature Burial", a short story by Edgar Allan Poe, the narrator talks about being in a state of suspended animation as a way of alluding death. At the time, the idea of suspended animation was not plausible.
The Terran's backstory from StarCraft talks of "The Long Sleep," a thirty-year long cryogenic hibernation as the result of a malfunctioning computer. The first mission of Episode V has the Adjutant offer the player "Cryostim supplements" to combat hybernation sickness.
In Warhammer 40,000, space marines are modified to be able to enter suspended animation when mortally wounded (the current record is 567 years, held by Silas Err), or extremely tired, which only lasts four hours.
In Orson Scott Card's book The Worthing Saga, a fictional drug called Somec is used to induce suspended animation for long periods of time.
In the Halo series, Cryo-chambers are used to put all crew into a deep sleep during faster-than-light travel, which may take months. In Halo 3, the Master Chief uses one to await rescue after becoming lost in space. He also awakens from a cryo-chamber at the beginning of Halo: Combat Evolved.
In the film Forever Young, Mel Gibson plays a 1939 test pilot who is voluntarily put in suspended animation after his fiancé winds up in a coma from a car crash. He is awakened fifty three years later by two boys to meet the 1990’s world.
In Final Fantasy VIII Sorceress Adel is placed in suspended animation by Laguna liberating Esthar from her rule.
Mr. Freeze, one of Batman's villans, has placed his beloved wife in suspended animation until a cure is found for her disease (often the motive of his crimes)
In the Star Trek episode "Space Seed" the Enterprise finds a sleeper ship launched from Earth during the Eugenics Wars in the 1990s containing Khan Noonien Singh and his band of followers, all cryogenically frozen.
At the end of Kingdom Hearts: Chain of Memories, Sora, Donald Duck and Goofy were put into suspended animation while their memories were restored and put back in order by Namine' the process would/did take a year to complete