A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
A new baby usually deprives each of it's parents around 350-400 hours of sleep in the first year. That is one entire nights sleep per week, per parent.
194
The human brain is more active during sleep than during the day.
28
The average person falls asleep in seven minutes.
115
Honeybees never sleep.
276
You burn more calories sleeping than you do watching television.
348
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