The human brain is more active during sleep than during the day.
28
Sleeping on the job is acceptable in Japan. It is viewed as exhaustion from working hard. Some people fake it to look committed to their job.
57
Lack of water is the #1 trigger of daytime fatigue.
148
There's a love mattress that is specifically designed for couples who sleep on each other's arms.
12
Blue light fends off drowsiness in the middle of the night, which could be useful to people who work at night.
240
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
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23