Microsleep

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A microsleep is an episode of sleep lasting from a fraction of a second up to several seconds. It often occurs as a result of sleep deprivation, or mental fatigue, sleep apnea, narcolepsy, or hypersomnia. People who experience excessive daytime sleepiness are at high risk for microsleep episodes.[citation needed]

Microsleeps can occur at any time, typically without significant warning. In the middle of even lively conversations, the onset of a microsleep episode can cause sufferers to 'suddenly' lose sync in a conversation. Not realizing their situation, they'll often rejoin a conversation with odd or poorly timed comments upon reawakening.[citation needed]

Microsleeps (or microsleep episodes) become extremely dangerous when occurring during situations which demand continual alertness, such as driving a motor vehicle or working with heavy machinery. People who experience microsleeps usually remain unaware of them, instead believing themselves to have been awake the whole time, or feeling a sensation of 'spacing out'. One example is called "gap driving": from the perspective of the driver, he or she was driving a car, and then suddenly realizes that several seconds have passed by unnoticed. It is not obvious to the driver that he 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. Many accidents and catastrophes have resulted from microsleep episodes in these circumstances.[1] For example, a microsleep episode is believed to have been one factor contributing to the Waterfall train disaster in 2003.

There is little agreement on how best to identify microsleep episodes. 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."[2]

[edit] References

  1. ^ 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. 
  2. ^ Paul, Amit; Linda Ng Boyle, Joh Tippin, Matthew Rizzo (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 on 2008-02-10.
  • (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
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