Microsleep[edit]

Microsleep is an episode of sleep which may last for a few seconds or several minutes.[1] Microsleeping can occur at any time, typically without significant warning.

Causes[edit]

Dangers[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. People who experience microsleeps usually remain unaware of them, believing to have been awake the whole time, or to have temporarily lost focus.

From the perspective of the operator of a motor vehicle that experiences microsleep, he or she is driving a car, and then realizes that several seconds have passed unnoticed. The microsleep is not realized by the driver. The 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] For example, a microsleep episode is claimed to have been one factor contributing to the Waterfall train disaster 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.

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."[4]