每當(dāng)看到蟲(chóng)子們那一對(duì)對(duì)大眼睛，我們都會(huì)產(chǎn)生疑惑，它們沒(méi)有眼皮，怎么睡覺(jué)呢？原來(lái)，這與快速動(dòng)眼期有關(guān)。這是一個(gè)睡眠的階段，是全部睡眠階段中最淺的，眼球在此階段快速移動(dòng)，大腦神經(jīng)元的活動(dòng)也與大腦清醒的時(shí)候相同，而這種現(xiàn)象發(fā)生在所有哺乳類動(dòng)物和鳥(niǎo)類動(dòng)物身上。

Ever wonder why bugs are so bug-eyed？

Night crawlers

While a still bug might look like dozing， the creepy crawler is merely relaxing. Neuroscientists distinguish sleep from rest by pointing to specific kinds of brain activity， like dreaming， that take place when the body is in an immobile state.

According to neurological criteria， insects do not actually sleep.

Neither do fish， amphibians or mollusks. Lizards and mammals， on the other hand， need to catch their z’s.

REM Sleep

REM， or Rapid Eye Movement， sleep is thought to be associated with dreaming， and is required by a particularly complex kind of brain. REM sleep is common to humans and nearly all mammals. Birds also get REM sleep， but only in the early part of their lives.

Koalas and Congressmen are alike that they both need their shut-eye to recharge， while your average mollusk and insect stay OPEN 24 hours a day.

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