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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The harder you concentrate on falling asleep, the less likely you are to fall asleep.
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Bats sleep 18-20 hours per day.
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44% of kids watch television before they go to sleep.
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Cows can sleep standing up, but they can only dream lying down.
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Honeybees never sleep.
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There's a love mattress that is specifically designed for couples who sleep on each other's arms.
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