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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Sea otters hold hands while sleeping so they don’t drift away from each other.
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The harder you concentrate on falling asleep, the less likely you are to fall asleep.
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Those who get out of bed by 7am are more likely to be thinner and happier.
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Sleeping on the job is acceptable in Japan. It is viewed as exhaustion from working hard. Some people fake it to look committed to their job.
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The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
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In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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