It's more than just feeling tired.

It's too early for a tension headache, but there are a few other reasons why you might wake up with a headache.

If anything, the constant auditory stimulation of white noise seems to disrupt sleep, suggests a meta-analysis of 38 studies.

When we cry, our heart rate increases and breathing slows down, reducing the amount of oxygen the brain receives, which leads to drowsiness.

There are behavioral and physiological components to the need to cover ourselves with a blanket or sheet while sleeping.

People have on average 4-6 dreams per night, and forget most of them.

Whether these technologies and techniques become accessible, affordable, and controllable in individual homes remains to be seen.

Turns out, choosing the right pillow for your body and sleep habits is exceedingly complicated.

A series in which The Swaddle team indulges your pity party with advice you'll probably ignore.

The act, known as pandiculating, is the body's way of restoring conscious, voluntary control over our muscles.

By afternoon, humans' circadian rhythm is in recharge mode, which makes us want to sleep.

Hypnic jerks are involuntary muscle movements that may have an evolutionary link to an ancient primate reflex.

Nightmares occur during R.E.M. sleep, when the brain's suppression systems relax and allow us process our feelings.

It's a kind of stress response called "learned helplessness" that renders the individual passive in the face of stress.

Sleep deprivation increases risk for a host of lifestyle disorders and shortens life spans.

Study participants who woke to a harsh, mechanical alarm reported feeling more groggy.

This biological rhythm controlled by the brain also influences appetite, body temperature, hormone levels, and blood pressure.

A stop-and-start breathing pattern may cause a sudden drop in blood oxygen levels, raising blood pressure and exerting the cardiovascular system.