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.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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The average cat sleeps about 2/3 of the day.
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Studies show that the colder the room you sleep in, the more likely you are to have a bad dream.
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Dieters who sleep more take off more fat that those who sleep less.
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A new parent will lose about 1055.6 hours of sleep in the first year of their child's life - almost 44 days!
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