One reason that kittens sleep so much is because a growth hormone is released only during sleep.
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Sea otters hold hands while sleeping so they don’t drift away from each other.
104
The human brain is more active during sleep than during the day.
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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
The average person falls asleep in seven minutes.
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In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34