2. The “natural alarm clock” which enables some people to wake up more or less when they want to is caused by a burst of the stress hormone adrenocorticotropin.
3. Tiny luminous rays from a digital alarm clock can be enough to disrupt the sleep cycle even if you do not fully wake. The light turns off a “neural switch” in the brain, causing levels of a key sleep chemical to decline within minutes.
4. Ducks at risk of attack by predators are able to balance the need for sleep and survival, keeping one half of the brain awake while the other slips into sleep mode.
5. Daytime naps improve memory! It also helps you remember important facts.
Naps also cut risk of heart disease.