1) When scientists destroyed the place of cats' brain that allowed REM sleep, they died.
2) There's something strange my prof. told me about the sleep cycle of an undomesticated cat, but I can't remember (I think they don't operate on any fixed schedule).
and
3) Left to their own devices, humans will adapt to a 25-hour day (meaning, if they don't know when it's "day" or "night" and just have to determine these themselves).
