NREM sleep


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Related to NREM sleep: Stages of Sleep

NREM sleep

(ĕn′rĕm′)
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

sleep

(slep)
A periodic state of rest accompanied by varying degrees of unconsciousness and relative inactivity. Although sleep is thought of as something that occurs once each 24-hr day, at least half of the world's population has an afternoon nap or siesta as part of their lifelong sleep-wake pattern. The need for and value of sleep is obvious; yet there is no explanation of why it provides a daily renewal of a feeling of health and well-being.

The sleep-wake cycle varies in relation to the age and gender of the individual. The newborn may sleep as much as 20 hr each day; a child, 8–14 hr, depending on age; adults, 3–12 hr with a mean of 7–8 hr, which may decrease to 6.5 hr in the elderly. Women over 35 tend to sleep more than men. There is great individual variation in the amount and depth of sleep.

Sleep has two states: non–rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep and REM sleep alternate during the night; each cycle requires 90–100 min. NREM sleep makes up approx. 75% of the sleep cycle, and REM sleep approx. 25%, with individual variations.

People deprived of sleep for several days or more become irritable, fatigued, unable to concentrate, and usually disoriented. Performance of mental and physical tasks deteriorates. Some people experience paranoid thoughts and auditory, visual, and tactile illusions or hallucinations. Deprivation of REM sleep may cause anxiety, overeating, and hypersexuality. The effects of sleep deprivation are reversed when the normal sleep-wake cycle is resumed. See: non–rapid eye movement sleep; rapid eye movement sleep

Physiological Changes during Sleep

The following physiological changes occur during sleep: body temperature falls; secretion of urine decreases; heart rate and respiration become slower and more regular during NREM sleep and then more rapid and less regular during REM sleep. During REM sleep, blood flow to the brain is increased; breathing is more irregular; heart rate and blood pressure vary; cerebral blood flow and metabolic rate increase; and penile erections may occur. There is an increased secretion of growth hormone during the first 2 hr of sleep; surges of adrenocorticotropic hormone (ACTH) and cortisol secretion occur in the last half of the sleep period. Luteinizing hormone secretion is increased during sleep in pubescent boys and girls, and prolactin secretion is increased in men and women, esp. immediately after the onset of sleep.

In evaluating sleep, it is important to know that hand waving, arm swinging, laughing, and flatus occur during normal sleep. Snoring may be clinically insignificant but, when accompanied by apnea, can be harmful.

dreaming sleep

Rapid eye movement sleep.

desynchronized sleep

Rapid eye movement sleep.

hypnotic sleep

1. Sleep induced by hypnotic suggestion.
2. Sleep induced by the use of medicines classified as hypnotics.

CAUTION!

Many hypnotic drugs are habit-forming.

light sleep

A colloquial term for the first stage of non–rapid eye movement (NREM) sleep. It is sometimes also applied to the second stage of NREM sleep.

non–rapid eye movement sleep

Abbreviation: NREM sleep
Sleep during which non–rapid eye movements occur. Dreams do not occur in NREM sleep. It has four stages: in stage 1, the transition from wakefulness to sleep occurs; eye movements are slow, and an electroencephalogram (EEG) shows low brain wave activity. In stage 2, EEG activity is increased, and spikes called K complexes appear. In stage 3, eye movement ceases; wave frequency is reduced and amplitude increased. In stage 4, the EEG is dominated by large spikes (delta rhythm). Stages 3 and 4 are considered deep sleep. Synonym: synchronized sleep See: rapid eye movement sleep; sleep

pathological sleep

Excessive or disordered sleep.

paradoxical sleep

A term sometimes used as a synonym for rapid eye movement (REM) sleep. REM sleep is the preferred term.

rapid eye movement sleep

Abbreviation: REM sleep
Sleep during which rapid eye movements occur. Dreams occur in REM sleep. It follows stage 4 of non–rapid eye movement (NREM) sleep; electroencephalographic activity is similar to that of NREM stage 1; and muscle paralysis normally occurs. Synonym: desynchronized sleep; dreaming sleep See: non–rapid eye movement sleep; sleep

synchronized sleep

Non–rapid eye movement sleep.

non–rapid eye movement sleep

Abbreviation: NREM sleep
Sleep during which non–rapid eye movements occur. Dreams do not occur in NREM sleep. It has four stages: in stage 1, the transition from wakefulness to sleep occurs; eye movements are slow, and an electroencephalogram (EEG) shows low brain wave activity. In stage 2, EEG activity is increased, and spikes called K complexes appear. In stage 3, eye movement ceases; wave frequency is reduced and amplitude increased. In stage 4, the EEG is dominated by large spikes (delta rhythm). Stages 3 and 4 are considered deep sleep. Synonym: synchronized sleep See: rapid eye movement sleep; sleep
See also: sleep
Medical Dictionary, © 2009 Farlex and Partners

Non-rapid eye movement (NREM) sleep

A type of sleep that differs from rapid eye movement (REM) sleep. The four stages of NREM sleep account for 75-80% of total sleeping time.
Mentioned in: Sleep Disorders
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
REM sleep episodes were more frequent (by 2.6 episodes) in the exposed group, and the mean duration of NREM sleep episodes was longer (by 1.0 min).
The cyclic alternating pattern as a physiologic component of normal NREM sleep. Sleep 1985; 8: 137-145, doi: 10.1093/sleep/8.2.137.
The following CAP variables were measured in the present study: CAP rate (percentage of total NREM sleep time occupied by CAP sequences); percentage and duration of each A phase subtype; A1, A2, and A3 index; number of phases A1, A2, or A3 per hour of NREM sleep; number and duration of CAP cycle; and number and duration of B phases.
Overall, NREM sleep variables were mostly influenced by GML, probably via synaptic potentiation mechanisms occurring after learning.
(5) NREM sleep stage 4 (NREM4): this stage is a continuation of deep sleep.
However, one study [134] revealed a weak correlation between the influence of drug therapy on reduction of nocturnal BP and frequency of apneic episodes during REM sleep in hypertensive OSA patients despite no change in AHI during NREM sleep or for the overall sleep duration.
But in our research and the preliminary study, we found it harder to induce arousals during REM sleep than during NREM sleep. The stimuli might be incorporated into the ongoing dream during REM sleep rather than producing an awakening [42].
In the first part of the present study, we have modeled the alternation of REM and NREM sleep starting from the classical Kuramoto model.
NREM sleep is further divided into three stages (NREM 1-3), which reflect different depths of sleep on a continuum.
In an animal model, total sleep time increases during pregnancy, with an early but transient increase in REM duration, a sustained increase in NREM sleep over the course of pregnancy, and increased diurnal sleep during late gestation.6
Dynamic central nervous system (CNS) changes that occur during both REM and NREM sleep may contribute to memory encoding, memory consolidation and reconsolidation as well as brain plasticity.
There are four stages of NREM sleep: Stage 1--light sleep, easily awakened, eye and muscle movement slow down; Stage 2--eye movements stop, brain waves slow with occasional rapid bursts; Stage 3--deep sleep, difficult to awaken, brain waves slow down more but have occasional rapid waves; and Stage 4--very deep sleep, difficult to awaken, extremely slow brain waves.