Role of the pineal gland in hibernators: a concept proposed to clarify why hibernators have to leave torpor and sleep.

The contention that torpor during hibernation might not be a kind of sleep but a kind of sleep deprivation may be correct, as it can be conceptually explained. Sleep is part of life and cannot be part of the torpor state, which has no reactions. The state of torpor has a time limit and, if this is not observed, death follows by freezing. The evolutional differences particularly in pineal gland physiology may explain the differences between the blueprints governing vital reflexes in humans and hibernators. Copyright 2000 Harcourt Publishers Ltd.