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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 ...
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]
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.
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
Sample hypnogram showing one sleep cycle (the first of the night) from NREM through REM. The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. 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 ...
Most of this awake time occurred shortly after REM sleep. [24] Today, many humans wake up with an alarm clock; [25] however, people can also reliably wake themselves up at a specific time with no need for an alarm. [24] Many sleep quite differently on workdays versus days off, a pattern which can lead to chronic circadian desynchronization.
Circadian rhythm sleep disorders (CRSD), also known as circadian rhythm sleep–wake disorders (CRSWD), are a family of sleep disorders that affect the timing of sleep. CRSDs cause a persistent pattern of sleep/wake disturbances that arise either by dysfunction in one's biological clock system, or by misalignment between one's endogenous oscillator and externally imposed cues.
After going through stages of REM-sleep, people with depression report feeling better, in a study done by Cartwright et al. [40] Conversely, a theory proposed by Revonsuo [41] states that when people experience negative emotions or negative events, when they sleep the REM-sleep replays such events, which is known as rehearsal. [39]