Suspended animation
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 though only provides a limited amount of time to operate and there is risk of tissue and brain damage for extended periods.

# Recent experiments

## Temperature induced suspended animation
In July 2005 scientists at the University of Pittsburgh's Safar Center for Resuscitation Research announced they had managed to bring dogs back to life, most of them without brain damage, by draining the blood out of the dogs' bodies and putting an ice cold solution into their circulatory systems, which in turn keeps the bodies alive in stasis. After 3 hours of being clinically dead, their blood was put back into their circulatory systems, and the dogs were revived by delivering an electric shock to their hearts. The heart started pumping the blood around the frozen body, and the dogs were brought back to life. Scientists hope to begin human testing and have already begun discussions with hospitals to use "suspended animation" if everything else fails.
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. Safar Research believes that the process is merely another way to give "more time" to the operation table, as vital repairs could be made when patients are in stasis: emergency operations fail frequently simply because of the lack of time, not the lack of expertise. This technique should be enough to save lives such as battlefield casualties and victims of stabbings or gunshot wounds, who have suffered huge blood loss.
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.

## Chemically induced suspended animation
An article in the April 22, 2005 issue of the scientific journal Science, reports success towards inducing suspended animation in mice. The findings are significant, as mice do not hibernate in nature. The laboratory of Mark Roth placed the mice in a chamber containing 80 ppm hydrogen sulfide for a duration of 6 hours. The mice's core body temperature dropped to 13 degrees Celsius and metabolism, as assayed by carbon dioxide production and oxygen use, decreased 10-fold.
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.

# Induced Human Hibernation
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.

# Suspended animation in fiction
Suspended animation is also a common device in fiction used to transport individuals from one time period to another, as in The Man Who Awoke, by Laurence Manning, or Dr. Evil in Austin Powers. In some cases, this would be a terminally ill person awaiting discovery of a cure for a currently incurable condition, as in A World Out of Time,  by Larry Niven and The Twilight Zone episode Quarantine. In "Sleeper", Woody Allen used suspended animation to bring a 1960's Greenwich Village health-food store owner 200 years into a future where fatty foods and cigarettes are noted for their health benefits.
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.
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 South Park episode Go God Go, Cartman practices suspended animation by freezing himself in the Rocky Mountains to avoid waiting for the release of Nintendo's Wii console.
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.
In Futurama, during the first episode, the central character Philip J. Fry is accidentally cryopreserved in year 2000, for 1000 years until year 3000, which is the setting for most of the show.
The premise for the television series Red Dwarf involved the main character, Dave Lister, being put in temporal Stasis as a 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.
Before the anime/manga InuYasha begins, the title character InuYasha was put in suspended animation by the priestess Kikyo, who died shortly after.
In Suspended, which was made by Infocom, the player's character is a person in suspended animation.
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, 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.
In The Empire Strikes Back, Han Solo is put into suspended animation by being frozen into a block of carbonite.
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 Diane Duane's Wizards at War, Nita Callahan puts her friend Ronan Nolan into a "stasis" so that he will not die as a result of having used the Spear of Destiny against himself.
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).
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 the computer game Homeworld, Kharak refugees are kept in suspended animation during the voyage to their homeworld planet, Hiigara.
In Namco's Tekken games, Nina Williams is placed in Cyrosleep Testing for not killing Kazuya Mishima. She wakes up 18 years later and mistakes Jin Kazama as Kazuya.
In the film Terrarium 12 astronauts are put in suspended animation for 15 years to reach a distant planet, Gallegos 39.
In the Halo series, Cryo-chambers are used to put all crew into a deep sleep during faster-than-light travel, which even may take months. At the end of Halo 3, the Master Chief uses one to await rescue, which could take years, after becoming lost in space.