Lack of water is the #1 trigger of daytime fatigue.
148
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
There's a love mattress that is specifically designed for couples who sleep on each other's arms.
12
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
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
You burn more calories sleeping than you do watching television.
348
Honeybees never sleep.
276