Suspended animation

Suspended animation is the technical term for the slowing without termination of life processes by external means. Outside science fiction, the technique is hypothetical. 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 had led to the developing science of cryonics.

Placing astronauts in suspended animation has been proposed as the only practical way for an individual to reach the end of an interplanetary or interstellar journey. It is also a common device in fiction used to transport individuals from one time period to another.

Among the characters or works that utilize suspended animation are:

• Edward Bellamy's 1887 novel Looking Backward
• Robert Heinlein's 1957 novel The Door Into Summer
• Captain America, who survived the end of World War II and was revived by the Avengers in the 1960s;
• Star Trek: The Original Series episode "Space Seed" and Star Trek: The Next Generation episode "The Neutral Zone", in which individuals from the late 20th century are revived three and four centuries later, respectively;
• Woody Allen's movie Sleeper