> She distilled a set of behavioral criteria to identify sleep without the EEG. A sleeping animal does not move around. It is harder to rouse than one that’s si

> She distilled a set of behavioral criteria to identify sleep without the EEG. A sleeping animal does not move around. It is harder to rouse than one that’s simply resting. It may take on a different pose than when awake, or it may seek out a specific location for sleep. Once awakened it behaves normally rather than sluggishly. ... A sleeping animal that has been disturbed will later sleep longer or more deeply than usual, a phenomenon called sleep homeostasis. When you define "sleep" this way, without reference to the brain or consciousness, it's not all that surprising that animals without brains can "sleep". If you take out the criteria having to do with locomotion, so as not to exclude organisms that don't need it, plants probably sleep too...