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
You forget 90% of your dreams.
256
In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
13
Honeybees never sleep.
276
Bats sleep 18-20 hours per day.
5
People who sleep late have more mental stamina and can outperform early risers.
33