腦子即使不做夢， 也不休息，腦子隻有死了才休息。身體別的器官需要休息。

http://advancedlifeskills.com/blog/what-is-your-brain-doing-while-you-are-sleeping/

During sleep our brain is, in fact, extraordinarily active. As it turns out, much of that activity helps the brain to learn and remember. Sleeping is involved in the learning and memory process in several important ways.