Defined as attentional lapses which are more than half a second and can last for significant numbers of seconds where the brain is unable to process the visual field data being “seen” by the eyes. ¬†Microsleeps are important in safety related tasks such as driving a vehicle and start infrequently but increase in duration and frequency as “time awake” or “high risk circadian times (nightime)” increase. ¬†They are more frequent during long periods of operation and when alone and operating in “boring” environments.


Fatigue can be caused by mental or physical activity, but it is the “sleep related” fatigue which creates the highest risks in safety operations, such as driving or operating heavy machinery.