Hibernation
The Silurians and Sea Devils went into hibernation after detecting a rogue planet on a course for Earth. (TV: Doctor Who and the Silurians [+]Loading...["Doctor Who and the Silurians (TV story)"], The Sea Devils [+]Loading...["The Sea Devils (TV story)"]) This was known as the great hibernation. (PROSE: The Scales of Injustice [+]Loading...["The Scales of Injustice (novel)"])
Sorvix automatically went into hibernation when they were sick whilst Mystics deliberately did so to find God. The Fallen Tyrant of Taladel was kept in a cocoon for 4,000 years before he was woken up and killed. (AUDIO: Aliens & Sex & Chips & Gravy [+]Loading...["Aliens & Sex & Chips & Gravy (audio story)"])