Microsleep

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 when there are sudden shifts between states of wakefulness and sleep.

[6][7][8][9][10] Microsleep is extremely dangerous when it occurs in situations that demand constant alertness, such as driving a motor vehicle or working with heavy machinery.

People who experience microsleeps often remain unaware of them, instead believing themselves to have been awake the whole time, or to have temporarily lost focus.

[11] With over 1,550 fatalities and 40,000 nonfatal injuries occurring annually in the United States alone as a result of drowsy driving, sleep loss has become a public health problem.

[16] For example, a microsleep episode is claimed to have been one factor contributing to the Waterfall rail accident in 2003; the driver had a heart attack, and the guard who should have reacted to the train's increasing speed is said by his defender to have microslept, thus causing him to be held unaccountable.

[24][verification needed] In one study, neural activity underlying microsleeps was investigated by simultaneously measuring eye video, response behavior, EEG, and fMRI in normally-rested individuals engaged in a sensory-motor task.

Most participants had frequent microsleeps (>35) in a continuous visuomotor task (tracking visual stimulus on a screen), corresponding with decreased activity in arousal-related brain regions over time (thalamus, midbrain, and the posterior cingulate cortex).

When this pathway is not activated, cells in the superior colliculus (which causes release of dopamine) cannot be dis-inhibited via the basal ganglia, leading to poor processing ability and microsleep onset.

More complex and expensive ways to detect microsleeps include EEG, fMRI, EOG, and PSG tied to various software platforms.

Sleep apnea is by far the most significant disease tied to microsleeps in terms of prevalence, affecting roughly 10–15 million people.

[43] Microsleeps that recur and negatively influence day-to-day living often are clustered into the category of excessive daytime sleepiness.

[54] Therefore, clinical interventions pertaining to microsleeps may also encompass reducing excessive sleepiness as a side effect of drug administration.