Flight operations often take place at night, which can disrupt the circadian rhythms responsible for monitoring sleep and wake cycles. The International Civil Aviation Organization (ICAO) defines<unk>  as "A physiological state of reduced mental or physical performance capability resulting from sleep loss or extended wakefulness, circadian phase, or workload." The phenomenon places great risk on the crew and passengers of an airplane because it significantly increases the chance of<unk>  error.<unk>  is particularly prevalent among<unk> s because of "unpredictable work hours, long duty periods, circadian disruption, and insufficient sleep". These factors can occur together to produce a combination of sleep deprivation, circadian rhythm effects, and 'time-on task'<unk> . Regulators attempt to mitigate<unk>  by limiting the number of hours<unk> s are allowed to fly over varying periods of time.
Pilot fatigue
Alarm fatigue
Sympathicolysis
Overpressure
Hypnic jerk
Peroneal strike
Simulator sickness
Contracture