There's a love mattress that is specifically designed for couples who sleep on each other's arms.
12
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
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
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People who sleep late have more mental stamina and can outperform early risers.
33
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
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