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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.
Studies using event-related potential (ERP) recordings have found that twenty-four hours of sleep deprivation decreases ERP response to signal inputs from endogenous, but not exogenous, sources. Therefore, it is suggested that sleep deprivation affects endogenously-driven selective attention to a greater extent than exogenously-driven selected ...
Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity, and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep, [1] and reduced interactions with surroundings. [2]
Deep sleep refers to slow-wave sleep — a stage in the sleep cycle when brain waves slow down. Getting enough deep sleep is crucial for numerous bodily functions.
Sleep increases the sensory threshold. In other words, sleeping persons perceive fewer stimuli, but can generally still respond to loud noises and other salient sensory events. [14] [12] During slow-wave sleep, humans secrete bursts of growth hormone. All sleep, even during the day, is associated with the secretion of prolactin. [15]
Sleep deprivation, also known as sleep insufficiency [2] or sleeplessness, is the condition of not having adequate duration and/or quality of sleep to support decent alertness, performance, and health. It can be either chronic or acute and may vary widely in severity.
Since the REM stages typically occur during the second half of sleep, sleeping too little may not allow the body enough time to complete all the REM sleep cycles, per the National Sleep Foundation.
A microsleep is a sudden temporary episode of sleep or drowsiness which may last for a few seconds where an individual fails to respond to some arbitrary sensory input and becomes unconscious. [ 1 ] [ 2 ] Episodes of microsleep occur when an individual loses and regains awareness after a brief lapse in consciousness, often without warning, or ...