Do all mammals have the same sleep pattern?
There's a huge variety of sleep across all mammals. So some mammals are nocturnal, they're active at night and sleep during the day. Most mammals in fact have highly disturbed and distributed sleep so a nocturnal mammal will also sleep during the night as well as being active during the night. Humans are almost the only mammal that tries to consolidate all of their sleep into one particular time. And even there, with the siesta cultures one doesn't see that. In fact if one goes back to the 19th century and looks at shepherding cultures, there they have a more distributed sleep pattern then we would regard as reasonable nowadays. So they're both different patterns of sleep. And also the biological clock runs at a different rate so the ultradian rhythm, the nineteen minute cycle that one sees within sleep is hugely faster in small brain species like mice and rats than in large brain species like dolphins and mammals. And it gets more complicated, if you look at dolphins and porpoises, so aquatic mammals, they in fact have a mechanism whereby one half of the brain goes to sleep whilst the other half remains awake and vice versa, and there's a cycle there as well.
