Sea otters hold hands while sleeping so they don’t drift away from each other.
104
Dieters who sleep more take off more fat that those who sleep less.
159
If you hold farts in during the day, they'll just come out when you sleep.
16
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
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 human brain is more active during sleep than during the day.
28
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212