The human brain is more active during sleep than during the day.
28
Lack of water is the #1 trigger of daytime fatigue.
148
Honeybees never sleep.
276
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Sleeping on your stomach can induce weirder, scarier, and sexier dreams.
22
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23