A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
"Dysania" is the state of finding it hard getting up out of bed in the morning.
33
Bats sleep 18-20 hours per day.
5
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
Lack of water is the #1 trigger of daytime fatigue.
148