Sleep stages

Measurement of muscle activity, usually measured by electrodes placed on the skin. The EMG is used in sleep research to aid in the discrimination of sleep stages, and also as part of diagnosis of sleep disorders such as periodic limb movements and restless legs syndrome. 

Rapid eye movement sleep. Sleep stage characterized by rapid movements of the eyes and asynchronous EEG activity in the theta-frequency (5-10Hz) range. Counterpart is slow wave sleep, characterized by other electrophysiological (synchronized low frequency l-2Hz, large amplitude EEG and neuronal sharp wave-ripple oscillations) and endocrine (growth hormone surge) activities. 

Since the publication of the Standardised Sleep Manual by Rechtshaffen and Kales (Eds) in 1968, human sleep has been described using a classification system based on a combination of EEG, EMG and EOG features. The acquisition and use of such data is known as polysomnography. Note, that when including the state of WAKE in the classification, these are most accurately described as arousal states in place of sleep stages. 

Oscillations in the EEG of between 0.5 and 4 Hz, sometimes also called delta activity. SWA is a hallmark of the sleeping brain, and is most prevalent in the deepest sleep stages (stages 3 4). The slow oscillations arise from widespread synchrony of neuronal firing, particularly in the thalamocortical circuits. 

Generic term usually applied to the deeper stages of NREM sleep (stages 3 and 4), so called because of the high proportion of slow wave activity (SWA). 

The etiology of enuresis is poorly understood, but there is a clear genetic link. The incidence in children from families in whom there are no members with enuresis, where one parent had enuresis as a child, and where both parents had enuresis as children are 14%, 44%, and 77%, respectively. Loci for enuresis have been located on chromosomes 12,13, and 22. Sleep disorders are not considered major contributors with the exception of sleep apnea. Enuresis occurs in all sleep stages in proportion to the time spent in each stage. However, a small proportion of individuals are not aroused from sleep by bladder distention and have uninhibited bladder contractions preceding enuresis. 

Nocturnal polysomnography Visual and electrophysiologic assessment of human sleep minimally composed of electroencephalogram, electrooculogram, and electromyogram that allows determination of sleep stage, breathing events, and muscle movements. 

Crouzier, D., Le Crom, V. B., Four, E., Lallement, G. 8r Testylier, G. (2004). Disruption of mice sleep stages induced by low doses of organophosphorus compound soman. Toxicology 199, 59-71. 

Stage 1 of NREM is the stage between wakefulness and sleep. Stage 3 and 4 sleep is called delta sleep (i.e., slow-wave sleep). 

Zolpidem, chemically unrelated to benzodiazepines or barbiturates, acts selectively at the y-aminobutyric acidA (GABAA)-receptor and has minimal anxiolytic and no muscle relaxant or anticonvulsant effects. It is comparable in effectiveness to benzodiazepine hypnotics, and it has little effect on sleep stages. Its duration is approximately 6 to 8 hours, and it is metabolized to inactive metabolites. Common side effects are drowsiness, amnesia, dizziness, headache, and GI complaints. Rebound effects when discontinued and tolerance with prolonged use are minimal, but theoretical concerns about abuse exist. It appears to have minimal effects on next-day psychomotor performance. The usual dose is 10 mg (5 mg in the elderly or those with liver impairment), which can be increased up to 20 mg nightly. Cases of psychotic reactions and sleep-eating have been reported. 

Clinical results with 20 have been recently reported from a phase I study that enrolled 70 healthy male human subjects. In this study, morning administration of the drug (200 mg and above) reduced alertness and latency to sleep stage 2 and increased time spent in sleep stage 2 with an overall improvement of sleep efficiency and total sleep time. These effects disappeared 6.5 h after drug administration [57],... 

A methodologically controlled study of valerian in sleep was published that utilized both double-blind and placebo controls, as well as randomization (Gessner and Klasser 1984). Also employed were two doses of valerian (60 and 120 mg), computerized EEG power spectral analysis and psychometric mood questionnaires. Valerian increased sleep stages 1, 2, and 3 and reduced stage 4 and REM. Dose-dependent effects were noted, where the 120 mg dose produced greater sedative effects. Peak effects occurred 2-3 hours after administration. Mood ratings did not differ, positively or negatively, between the experimental and control conditions. 

Infants are able to acquire odor preferences on the first day of life. In one experiment, 12 male and 12 female white, healthy, full-term neonates were exposed to the odors of cherry or ginger on a pad taped to the inside of their crib for 24 hours. After this exposure, they were tested for preferences during active sleep (stage II). The behavior was videotaped and the duration of time oriented to each odor measured. Only the female neonates showed a preference for the familiar odor (Balogh and Porter, 1986). Therefore, even on the first day of life, females outperform males, as often described for children and adults (e.g. Yousem etal, 1999). 

RechtschalFen, A. 8c A. Kales (1968). A manual of standardised terminology, techniques and scoring system for sleep stages of human subjects. UCLA Brain Information Service/Brain Research Institute, Los Angeles. 

Experimental and clinical evidence concerning the neurochemical state of the cortex during REM sleep suggests that the mentation of dreaming in this sleep stage can be characterised by the equation (Gottesmann, 2000) ... 

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