REM SLEEP – TYPES AND STAGES OF SLEEP
REM sleep is most easily recognized by the rapid and apparently random side-to-side movements of the closed eyes
REM sleep occurs in cycles of about 90-120 minutes throughout the night, and it accounts for up to 20-25% of total sleep time in adult humans, although the proportion decreases with age (a newborn baby may spend 80% of total sleep time in the REM stage). In particular, REM sleep dominates the latter half of the sleep period, especially the hours before waking, and the REMcomponent of each sleep cycle typically increases as the night goes on.
As the name suggests, it is associated with rapid (and apparently random) side-to-side movements of the closed eyes, a phenomenon which can be monitored and measured by a technique called electrooculography (EOG). This eye motion is not constant (tonic) but intermittent (phasic). It is still not known exactly what purpose it serves, but it is believed that the eye movements may relate to the internal visual images of the dreams that occur during REM sleep, especially as they are associated with brain wave spikes in the regions of the brain involved with vision (as well as elsewhere in the cerebral cortex).
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Brain activity during REM sleep is largely characterized by low-amplitude mixed-frequency brain waves, quite similar to those experienced during the waking state – theta waves, alpha waves and even the high frequency beta waves more typical of high-level active concentration and thinking. These show up as the typical “saw-tooth” brain wavepattern on an electroencephalogram (EEG) and, because of these similarities with the waking state, REM sleep has earned the moniker “paradoxical sleep”. The brain’s oxygen consumption, reflecting its energy consumption, is also very high during this period, in fact often higher than when awake and working on a complex problem.
REM SLEEP – TYPES AND STAGES OF SLEEP REM sleep is most easily recognized by the rapid and apparently random side-to-side movements of the closed eyes REM sleep occurs in cycles of about 90-120 minutes throughout the night, and it accounts for up to 20-25% of total sleep time in adult humans, although the proportion decreases with age (a newborn baby may spend 80% of total sleep time in the REM stage). In particular, REM sleep dominates the latter half of the sleep period, especially the hours before waking, and the REMcomponent of each sleep cycle typically increases as the night goes on. As the name suggests, it is associated with rapid (and apparently random) side-to-side movements of the closed eyes, a phenomenon which can be monitored and measured by a technique called electrooculography (EOG). This eye motion is not constant (tonic) but intermittent (phasic). It is still not known exactly what purpose it serves, but it is believed that the eye movements may relate to the internal visual images of the dreams that occur during REM sleep, especially as they are associated with brain wave spikes in the regions of the brain involved with vision (as well as elsewhere in the cerebral cortex). [quads id=1] Brain activity during REM sleep is largely characterized by low-amplitude mixed-frequency brain waves, quite similar to those experienced during the waking state – theta waves, alpha waves and even the high frequency beta waves more typical of high-level active concentration and thinking. These show up as the typical “saw-tooth” brain wavepattern on an electroencephalogram (EEG) and, because of these similarities with the waking state, REM sleep has earned the moniker “paradoxical sleep”. The brain’s oxygen consumption, reflecting its energy consumption, is also very high during this period, in fact often higher than when awake and working on a complex problem.