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
Cows can sleep standing up, but they can only dream lying down.
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Sea otters hold hands while sleeping so they don’t drift away from each other.
104
47% of people have a nightmare at least once a month.
186
You forget 90% of your dreams.
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The human brain is more active during sleep than during the day.
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