The average cat sleeps about 2/3 of the day.
203
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
Lack of water is the #1 trigger of daytime fatigue.
148
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
The strangers in your dreams are actually people that you've seen in real life.
50
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212