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
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
A new parent will lose about 1055.6 hours of sleep in the first year of their child's life - almost 44 days!
6
Dieters who sleep more take off more fat that those who sleep less.
159
The strangers in your dreams are actually people that you've seen in real life.
50
Lack of water is the #1 trigger of daytime fatigue.
148
You forget 90% of your dreams.
256