Some people have a "natural alarm clock" allowing them to wake up when they want. This is actually caused by a burst of the stress hormone adrenocorticotropin.
15
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Termites work 24 hours per day and they do not sleep.
57
Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
28
Honeybees never sleep.
276
The higher someone’s I.Q. the more likely they are to be sleep deprived.
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