Cryosleep System
Cryosleep (cryo) systems are life support systems designed to place biological individuals into suspended animation, usually to facilitate interstellar travel. With the advent of affordable life extension technology throughout humanity, cryosleep systems act less to preserve lifespan and more to reduce the tedium of spending multiple years or even decades confined within a ship, with catastrophic effects to the mental health of crew members. They also conserve resources, allowing ships to be lighter without oxygen reserves, hydroponics farms, and entertainment amenities for the entire travel period. The largest manufacturers of cryosleep systems include Pacific Industrial Science, Clare Biomedical, and BioCorp. The systems were theorised during the 21st and 22nd centuries, but not put into practice until the Thetis Program in the mid-23rd century.
Procedure
The majority of cryosleep systems require a medical procedure conducted by technicians to initiate the suspension process, which involves initial sedation, the placement of IVs, and the replacement of blood with cryoprotectants before the body is flash-frozen within the cryopod enclosure; at the end of the cryosleep period, the individual is defrosted and revived automatically by the pod without the need for manual intervention. Because of the requirement of technician intervention to place individuals back in suspension, ship medical crews usually employ at least one synthetic to act as the last individual to "go back to sleep", as synthetics can place themselves in hibernation and do not require cryopods.
Cryosleep systems are designed to not require active power to maintain freezing temperatures. While active cooling systems are used in atmospheric environments, in space passive / unpowered heat exchangers are used to ensure the interior of the cryopod remains at the same temperature as the space outside the ship. There is no danger of a power failure resulting in the immediate deaths of crew members, unless that failure occurs on the ground.