![]() ![]() Monoamines are active during NREMS, but not REMS, whereas acetylcholine is more active during REMS. Researchers have proposed different models to elucidate the undoubtedly complex rhythm of electrochemical processes that result in the regular alternation of REM and NREM sleep. In humans, the transition between non-REM and REM is abrupt in other animals, it is less so. Alternation between the stages therefore maintains body temperature within an acceptable range. Thus, during REM sleep, body temperature tends to drift away from its mean level, and during non-REM sleep, to return to normal. Homeostatic functions, especially thermoregulation, occur normally during non-REM sleep, but not during REM sleep. Moreover, methods based on cardiorespiratory parameters are also effective in the analysis of sleep architecture-if they are associated with the other aforementioned measurements (such as electroencephalography, electrooculography and the electromyography). ĮOG (electrooculography), the measure of the eyes’ movement, is the third method used in the sleep architecture measurement for example, REM sleep, as the name indicates, is characterized by a rapid eye movement pattern, visible thanks to the EOG. 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, and during REM sleep, there is a state of muscle atonia (paralysis), resulting in an absence of signals in the EMG. In order to determine in which stage of sleep the asleep subject is, electroencephalography is combined with other devices used for this differentiation. ![]() ![]() Heart rate variability, well known to increase during REM, predictably also correlates inversely with delta-wave oscillations over the ~90-minute cycle. Secretions of various hormones, including renin, growth hormone, and prolactin, correlate positively with delta-wave activity, while secretion of thyroid-stimulating hormone correlates inversely. Delta wave activity, correlating with slow-wave (deep) sleep, in particular shows regular oscillations throughout a good night's sleep. Characteristics Įlectroencephalography shows the timing of sleep cycles by virtue of the marked distinction in brainwaves manifested during REM and non-REM sleep. In humans, this cycle takes 70 to 110 minutes (90 ± 20 minutes). It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. Sample hypnogram showing one sleep cycle (the first of the night) from NREM through REM ![]()
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