A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
You forget 90% of your dreams.
256
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
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
Lack of water is the #1 trigger of daytime fatigue.
148