Sleep is a normal, recurrent state of human physiology accompanied by complex changes in brain activity. Other changes include hormone fluctuations and a relaxation of the musculature. Although the purpose of sleep is still largely unknown, it is clear that it influences the rest of the body’s physiology, including cognition. Sleep is a vital period of human life, and it affects both physical and mental health.

There are several theories about why sleep is important for our health and wellbeing. One theory posits that we sleep in order to conserve energy. Another is the restorative theory, which argues that sleep is necessary to rejuvenate the body. A third theory claims that sleep is important for the brain because it helps neurons reorganize. Another theory says that during sleep, the brain’s glymphatic system cleans out waste and toxins from the central nervous system, which helps the brain to function better while awake.

Research shows that the brainstem, a structure in the brain, plays an important role in sleep. It communicates with the hypothalamus, which produces a chemical called GABA that quiets the body’s arousal centers. In REM sleep, the brainstem sends signals to paralyze the muscles of the body to prevent dreaming.

The brain is involved in the regulation of the immune system and supports the functioning of nearly every part of the body. When sleep is insufficient, the body’s immunity and metabolism are compromised, and symptoms of depression, high blood pressure, diabetes, and migraines can increase. Lack of sleep can even cause the onset of a pre-diabetic condition.

Researchers have found that REM sleep can be either intermittent or continuous. The tonic type has low EEG and suppressed muscle tone, whereas the intermittent type contains intermittent events. Most of the muscles are paralyzed during the REM stage to prevent the body from flailing in response to dream content. The REM stage is also associated with rapid eye movements and spike-like electrical activity in the brain regions of the cerebral cortex.

The biological clock controls growth, reproductive cycles, and aging. The clock also controls sleep and wakefulness. This cycle is known as circadian rhythms. In humans, the drive for sleep follows this cycle. Changing the temperature of the bedroom or taking a hot bath may improve sleep quality. Besides, a cool room can help you sleep better.

While sleeping, we move through three to five different stages during the night. The first REM stage may last a few minutes, but it becomes longer with each subsequent cycle. The N3 stage tends to be shorter. If you miss a REM stage, you will try to make it up the following night. However, you may not be able to achieve a full REM sleep every night. If you are having trouble falling asleep, you may be suffering from insomnia.

Many adults in the United States experience a change in their sleep pattern. While they typically get seven hours of sleep at night, the majority of them do not get the recommended eight hours of sleep a day. Sleep deprivation is linked to increased risk for various chronic diseases, obesity, and mental disorders. For these reasons, proper sleep hygiene is crucial to maintaining health.