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Free-running sleep is a rare sleep pattern whereby the sleep schedule of a person shifts later every day. [1] It occurs as the sleep disorder non-24-hour sleep–wake disorder or artificially as part of experiments used in the study of circadian and other rhythms in biology .
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]
Hori et al. regard sleep onset hypnagogia as a state distinct from both wakefulness and sleep with unique electrophysiological, behavioral and subjective characteristics, [10] [12] while Germaine et al. have demonstrated a resemblance between the EEG power spectra of spontaneously occurring hypnagogic images, on the one hand, and those of both ...
One of the important questions in sleep research is clearly defining the sleep state. This problem arises because sleep was traditionally defined as a state of consciousness and not as a physiological state, [14] [15] thus there was no clear definition of what minimum set of events constitute sleep and distinguish it from other states of partial or no consciousness.
Sleep inertia is a physiological state of impaired cognitive and sensory-motor performance that is present immediately after awakening. It persists during the transition of sleep to wakefulness, where an individual will experience feelings of drowsiness, disorientation and a decline in motor dexterity.
After sustained periods of sleep, both the speed and synchronicity of the neurons firing are shown to decrease. [5] Another effect of wakefulness is the reduction of glycogen held in the astrocytes, which supply energy to the neurons. Studies have shown that one of sleep's underlying functions is to replenish this glycogen energy source. [6]
The term polyphasic sleep was first used in the early 20th century by psychologist J. S. Szymanski, who observed daily fluctuations in activity patterns. [2] It does not imply any particular sleep schedule. The circadian rhythm disorder known as irregular sleep-wake syndrome is an example of polyphasic sleep in
Sleeping can be described as the lack of conscious awareness of the outside world, meaning large portions of the brain that receive and interpret signals are deactivated during this time, while dreaming is a specific state of sleep in which enhanced brain activity has been shown to occur, [1] theorizing the primary consciousness could be active ...