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
Lack of water is the #1 trigger of daytime fatigue.
148
Bats sleep 18-20 hours per day.
5
Cows can sleep standing up, but they can only dream lying down.
745
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