Sleeping

Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep, and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than a coma or disorders of consciousness, with sleep displaying very different and active brain patterns.

Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body. A well-known feature of sleep is the dream, an experience typically recounted in narrative form, which resembles waking life while in progress, but which usually can later be distinguished as fantasy.

During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems. The internal circadian clock promotes sleep daily at night. The diverse purposes and mechanisms of sleep are the subject of substantial ongoing research. Humans may suffer from various sleep disorders, including Insomnia, sleep apnea, Narcolepsy, and sleep paralysis.

Sleep Cycle

Sleep is divided into two broad types: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Each type has a distinct set of physiological, neurological, and psychological features. NREM and REM sleep are so different that they could be considered two distinct behavioral states.

Sleep Disorders

Sleep disorders are a group of conditions that affect the ability to sleep well on a regular basis. Whether they are caused by a health problem or by too much stress, sleep disorders are becoming increasingly common. They can interfere with not only physical health but also emotional health.

See Also

• Circadian rhythm
• Dream
• Insomnia
• Narcolepsy
• Sleep apnea
• Sleep paralysis

Sleeping Resources
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