A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The average person falls asleep in seven minutes.
115
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
The higher someone’s I.Q. the more likely they are to be sleep deprived.
29
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
There's a love mattress that is specifically designed for couples who sleep on each other's arms.
12
47% of people have a nightmare at least once a month.
186