Until the 1950s it was generally believed that the brain essentially shuts off during sleep, but this is now known to be far from true; activity continues, but patterns become very different.
直到1950年代，人们大多相信在睡眠期间脑是基本上处于关闭状态的，现在人们知道这和事实差距很大；脑活动在睡眠时继续，但是模式变得非常不同。