Related topics: sleep

The shape of dogs' heads affects their sleep, according to study

Flat-faced dog breeds are popular all over the world. In the U.S. and in Hungary, the French bulldog is currently the most common breed. However, their popularity comes at a high cost in terms of health: Shortened skulls ...

Do wolves sleep like dogs?

Researchers at the Department of Ethology at Eötvös Loránd University, Hungary, have measured the sleep of the dog's wild counterpart, the wolf, for the first time. Their new study was published in Scientific Reports.

Octopuses have two alternating sleep states, study shows

Octopuses are known to sleep and to change color while they do it. Now, a study publishing March 25 in the journal iScience finds that these color changes are characteristic of two major alternating sleep states: an "active ...

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Rapid eye movement sleep

Rapid eye movement (REM) sleep is a normal stage of sleep characterized by rapid movements of the eyes. REM sleep is classified into two categories: tonic and phasic. It was identified and defined by Kleitman and Aserinsky in the early 1950s.

Criteria for REM sleep includes not only rapid eye movements, but also low muscle tone and a rapid, low voltage EEG -- these features are easily discernible in a polysomnogram, the sleep study typically done for patients with suspected sleep disorders.

REM sleep in adult humans typically occupies 20-25% of total sleep, about 90-120 minutes of a night's sleep. During a normal night of sleep, humans usually experience about 4 or 5 periods of REM sleep; they are quite short at the beginning of the night and longer toward the end. Many animals and some people tend to wake, or experience a period of very light sleep, for a short time immediately after a bout of REM. The relative amount of REM sleep varies considerably with age. A newborn baby spends more than 80% of total sleep time in REM. During REM, the activity of the brain's neurons is quite similar to that during waking hours; for this reason, the sleep stage may be called paradoxical sleep. This means that there are no dominating brain waves during REM sleep.

REM sleep is physiologically different from the other phases of sleep, which are collectively referred to as non-REM sleep (NREM). Vividly recalled dreams mostly occur during REM sleep.

This text uses material from Wikipedia, licensed under CC BY-SA