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A microsleep is an episode of sleep which may last for a fraction of a second or up to thirty seconds.[1] Often, it is the result of sleep deprivation, mental fatigue, depression, sleep apnea, hypoxia, narcolepsy, or hypersomnia. Microsleeping can occur at any time, typically without significant warning.People who experience microsleeps usually remain unaware of them, instead believing themselves to have been awake the whole time, or to have temporarily lost focus.

Safety Risks[edit]

Microsleeps (or microsleep episodes) become extremely dangerous when occurring during situations which demand constant alertness, such as driving a motor vehicle or working with heavy machinery. When experiencing microsleeps while driving an automobile, the driver does not realize when a microsleep begins occurring, but suddenly realizes after that several seconds have passed by. It is not obvious to the driver that he or she was asleep during those missing seconds, although this is in fact what happened. The sleeping driver is at very high risk for having an accident during a microsleep episode.[2]Many accidents and catastrophes have resulted from microsleep episodes in these circumstances.[3]


There is little agreement on how best to identify microsleep episodes. They are most common at times when the human body is "programmed" to sleep, such as in the morning.[4] Some experts define microsleep according to behavioral criteria (head nods, drooping eyelids, etc.), while others rely on EEG markers. One study at the University of Iowa defined EEG-monitored microsleeps in driving simulation as "a 3–14 second episode during which 4–7 Hz (theta) activity replaced the waking 8–13 Hz (alpha) background rhythm."[5]

See also[edit]


  1. ^ International Classification of Sleep Disorders Diagnostic and Coding Manual,, page 343
  2. ^
  3. ^ Blaivas AJ, Patel R, Hom D, Antigua K, Ashtyani H (2007). "Quantifying microsleep to help assess subjective sleepiness". Sleep Med. 8 (2): 156–9. doi:10.1016/j.sleep.2006.06.011. PMID 17239659. 
  4. ^
  5. ^ Paul, Amit (2005). "Variability of driving performance during microsleeps" (PDF). Proceedings of the Third International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design. Retrieved 2008-02-10.  Unknown parameter |coauthors= ignored (|author= suggested) (help)[dead link]
  • PMID 12530990 Ogilvie RD. The process of falling asleep. Sleep Med Rev 5: 247–270, 2001
  • PMID 14592362 Microsleep and sleepiness: a comparison of multiple sleep latency test and scoring of microsleep as a diagnostic test for excessive daytime sleepiness. 2003
  • PMID 15320529 Microsleep from the electro- and psychophysiological point of view. 2003