A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The record for the longest scientifically documented period without sleep is 264.4 hours (eleven days).
15
The strangers in your dreams are actually people that you've seen in real life.
50
You burn more calories sleeping than you do watching television.
348
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
47% of people have a nightmare at least once a month.
186