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NREM Stage 1 (N1 – light sleep, somnolence, drowsy sleep – 5–10% of total sleep in adults): This is a stage of sleep that usually occurs between sleep and wakefulness, and sometimes occurs between periods of deeper sleep and periods of REM. The muscles are active, and the eyes roll slowly, opening and closing moderately.
Deep sleep stages III and IV all occur during the first half of the night, while lighter stages I and II occur during the later half. During standard sleep laboratory measurements, the states of sleep and waking have behavioral , polygraphic, and psychological manifestation within the pontine brainstem.
EMG (electromyography) is a crucial method to distinguish between sleep phases: for example, a decrease of muscle tone is in general a characteristic of the transition from wake to sleep, [5] [6] and during REM sleep, there is a state of muscle atonia (paralysis), resulting in an absence of signals in the EMG. [5]
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, [1] and reduced interactions with surroundings. [2] An essential aspect of sleep is that it provides ...
Serotonin levels (in the form of 5-HT) have been shown to decrease during REM and NREM sleep, leading some researchers to believe that it is also involved in memory consolidation during sleep [citation needed]. Mice lacking the receptor gene for 5-HT engage in more REM sleep and perform better on spatial memory tasks. [48]
Dreaming occurs during both sleep states, and muscles are not paralyzed as in REM sleep. People who do not go through the sleeping stages properly get stuck in NREM sleep, and because muscles are not paralyzed a person may be able to sleepwalk. According to studies, the mental activity that takes place during NREM sleep is believed to be ...
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Polysomnography (PSG) is a multi-parameter type of sleep study [1] and a diagnostic tool in sleep medicine.The test result is called a polysomnogram, also abbreviated PSG.The name is derived from Greek and Latin roots: the Greek πολύς (polus for "many, much", indicating many channels), the Latin somnus ("sleep"), and the Greek γράφειν (graphein, "to write").