Sea otters hold hands while sleeping so they don’t drift away from each other.
104
People who sleep late have more mental stamina and can outperform early risers.
33
The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
The harder you concentrate on falling asleep, the less likely you are to fall asleep.
34
Bats sleep 18-20 hours per day.
5
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