Sleep is a natural state of bodily rest observed throughout the animal kingdom. It is common to all mammals and birds, and is also seen in many reptiles, amphibians and fish.

Read about how to get a healthy nights sleep, how much sleep is enough, and why skimping on sleep can lead to poor performance, health, and moods.

A sleep disorder (somnipathy) is a medical disorder of the sleep patterns of a person or animal. Some sleep disorders are serious enough to interfere with normal physical, mental ...

On-line web source for abstracts of articles published in SLEEP, the official journal of the American Sleep Disorders Association (www.asda.org) and the Sleep Research Society ...

Fact sheet on normal sleep and sleep disorders developed by the National Institute of Neurological Disorders and Stroke (NINDS).