Ripley in hypersleep

Ellen Ripley in a hypersleep capsule.

Stasis, known in practical applications as hypersleep, cryosleep or simply cryo, is a process that denotes the suspension of the passage of time for an object, typically a living subject. Its most common application is in long-distance interstellar travel, which — even at faster-than-light speeds — can take months or even years to achieve.


Stasis primarily revolves around the use of hypersleep chambers, simple cots with glass lids inside which crew members "sleep" for a large part of the duration of long-haul interstellar flights. During this sleep, the crew are effectively shielded from the effects of time, experiencing nothing and growing no older as time outside the cryotube passes normally. Although essentially "frozen" in this state, people in hypersleep are still capable of dreaming; indeed, dreaming is actively encouraged and apparently consciously pursued as a means to preserve the individual's mental health throughout long periods in cryo.[1] Owing to the way in which the processes of the human body are drastically slowed in hypersleep, these dreams can sometimes last for a year or more.[2]

While individuals in cryo are removed from the effects of time, long periods of hypersleep can cause muscle tone to break down, often leading to cramps and the diminishing of physical abilities upon waking.[3] Even so, cryotubes are effective to the point of being able to sustain and suspend an individual for decades, although waking from such a lengthy period of stasis carries with it minor side effects, including nausea, exhaustion and dizziness, that may last for several days.[4] Being removed from stasis abruptly without a proper wake-up procedure is dangerous, and while not usually fatal, it can lead to latent respiratory and circulatory complications, as well as cellular disruptions that may not manifest themselves until days or even weeks after the event.[5] Outwardly, this damage typically manifests itself as similar feelings of nausea, physical exhaustion and dizziness as are caused by unusually extended periods of hypersleep, although the symptoms are more acute.[6]

While an individual cryotube can only sustain a single person, it is common practice for smaller organisms to share a chamber with humans; for example, Jones the cat shared a tube with a human crew member during the USCSS Nostromo's long voyages without problems.[7]

The benefits of stasis are twofold; not only does it prevent crew members from wasting large portions of their lifespan on travel, it also reduces the amount of food, water and other consumables required on long trips, thereby saving considerable weight and storage space on board the ship. Vessels are generally not fully heated while the crew is in hypersleep, conserving valuable energy.[8] Furthermore, as the vast majority of space flight is uneventful and straightforward, the vessel can be piloted by the on-board computer and as a result the human crew are not required to operate the ship's systems. However, the need for a trained crew during docking and landing procedures means that human personnel cannot be removed entirely. Similarly, unforeseen events may lead to the need for human intervention during the course of the journey. Stasis allows for the crew to be available at the required times, while also relieving them of their duty during the extended periods when they are not needed to operate the ship.

Behind the Scenes

The mechanics of stasis are never explicitly explored in the Alien franchise, although the novelization of Alien mentions that the process involves lowering the body's core temperature considerably.[9] The novelization of Aliens additionally states that hypersleep involves the use of drugs injected into the body.[10] Traditional science fiction concepts for stasis revolve around either biologically-induced deep sleep or the use of artificial energy fields that suspend time for anything that they encapsulate. Which of these hypersleep in the Alien universe relies on, or whether it uses some other means, is never elaborated upon.

The novelization of the first film presents a different method of hypersleep to its film counterpart, wherein the hypersleep chambers are said to fill with a viscous liquid when in operation, and upon waking the crew has to wipe themselves down to remove the remains of this fluid.[8] Such a mechanism has been seen in other science fiction movies, such as Event Horizon.


  • The novel Predator: Incursion mentions that people in hypersleep do not dream. However, Prometheus shows that people do experience dreams in hypersleep, as David reviews Shaw's dreams during the trip to LV-223. The novelizations of Alien, Aliens and Alien3 also quite clearly state that people dream whilst in hypersleep, and that this process is in fact essential to the occupant's mental health during extended space travel.




  1. Alan Dean Foster. Alien, p. 11 (2014), Titan Books.
  2. Alan Dean Foster. Alien3, p. 8 (2014), Titan Books.
  3. Alan Dean Foster. Alien, p. 179 (2014), Titan Books.
  4. James Cameron (writer and director). Aliens (1986), 20th Century Fox [DVD].
  5. Alan Dean Foster. Alien3, p. 36 (2014), Titan Books.
  6. Vincent Ward (writer), David Fincher (director). Alien3 (1992), 20th Century Fox [DVD].
  7. Alan Dean Foster. Alien, p. 16 (2014), Titan Books.
  8. 8.0 8.1 Alan Dean Foster. Alien, p. 13 (2014), Titan Books.
  9. Alan Dean Foster. Alien, p. 14 (2014), Titan Books.
  10. Alan Dean Foster. Aliens, p. 8 (2014), Titan Books.
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