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Wakefulness is a daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world. Being awake is the opposite of being asleep , in which most external inputs to the brain are excluded from neural processing.
During sleep, there is a marked decrease in muscle activity and interactions with the surrounding environment. While sleep differs from wakefulness in terms of the ability to react to stimuli, it still involves active brain patterns, making it more reactive than a coma or disorders of consciousness. [1]
Hypnagogia is the transitional state from wakefulness to sleep, also defined as the waning state of consciousness during the onset of sleep.Its corresponding state is hypnopompia – sleep to wakefulness.
REM sleep is characterized by high global cerebral blood flow, comparable to wakefulness. [79] In fact, many areas in the cortex have been recorded to have more blood flow during REM sleep than even wakefulness- this includes the hippocampus, temporal-occipital areas, some parts of the cortex, and basal forebrain.
Similarly inhibition or reduction of mechanisms causing sleepiness, or drowsiness such as certain cytokines and adenosine (as with caffeine) may also increase perceived wakefulness and thus alertness. [ambiguous] [2] [3] [4] Wakefulness depends on the coordinated effort of multiple brain areas. These are affected by neurotransmitters and other ...
Sleep onset is the transition from wakefulness into sleep. Sleep onset usually transits into non-rapid eye movement sleep (NREM sleep) but under certain circumstances (e.g. narcolepsy) it is possible to transit from wakefulness directly into rapid eye movement sleep (REM sleep).
Two other neurotransmitters, orexin and gamma-Aminobutyric acid (GABA), seem to promote wakefulness, diminish during deep sleep, and inhibit paradoxical sleep. [ 3 ] [ 26 ] Unlike the abrupt transitions in electrical patterns, the chemical changes in the brain show continuous periodic oscillation.
In sleep science, sleep onset latency (SOL) is the length of time that it takes to accomplish the transition from full wakefulness to sleep, normally to the lightest of the non-REM sleep stages. [ 2 ]