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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. [1] [2] [3] [4]
Since this system is thought to modulate wakefulness and sleep, interference with it, such as injury, illness, or metabolic disturbances, could alter the level of consciousness. [ 9 ] Normally, stupor and coma are produced by interference with the brain stem , such as can be caused by a lesion or indirect effects, such as brain herniation . [ 9 ]
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.) Mental phenomena that may occur during this "threshold consciousness" include hallucinations, lucid dreaming, and sleep paralysis.
This system of a sort of general activation of consciousness is called "arousal" or "wakefulness". [14] It is not necessarily accompanied by drowsiness. [16] Patients may be awake (not sleepy) yet still have a clouded consciousness (disorder of wakefulness). [17] Paradoxically, affected individuals say that they are "awake but, in another way ...
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 ...
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]
Arousal is the physiological and psychological state of being awoken or of sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the brain, which mediates wakefulness, the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, desire ...
Representation of consciousness from the 17th century by Robert Fludd, an English Paracelsian physician. Consciousness, at its simplest, is awareness of internal and external existence. [1] However, its nature has led to millennia of analyses, explanations, and debate by philosophers, scientists, and theologians.