HALF AWAKE

摘要

Sleep feels like an on-or-off condition,but brains can be awake and asleep at the same time.This phenomenon is well known in dolphins and seals, "uni-hemispherically":one half of their brain is asleep while the other half shows electrical activity characteristic of wakefulness. A study in rats published last year found that after prolonged wakefulness some neurone go offline and display sleep-like activity(Nature,vol 472,p 443.