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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Lack of water is the #1 trigger of daytime fatigue.
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Dieters who sleep more take off more fat that those who sleep less.
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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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If you hold farts in during the day, they'll just come out when you sleep.
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The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
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