“All we know is that we need sleep. Our survival probably depends on it. If you keep rats awake, they die within two to four weeks. Of course, in order to prevent the poor creatures from sleeping, the scientists have to make it impossible for them to drop off, and some have questioned whether the animals die of stress rather than sleep deprivation. Fruit flies and cockroaches also perish when kept awake.”

So, what is sleep? Find out more …

What Is Sleep? – Opinionator Blog – NYTimes.com