Lack of water is the #1 trigger of daytime fatigue.
148
The human brain is more active during sleep than during the day.
28
Sea otters hold hands while sleeping so they don’t drift away from each other.
104
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
Termites work 24 hours per day and they do not sleep.
57