Stress, Fatigue and Sleep
This domain tests stress, fatigue and sleep: how arousal affects performance, how fatigue accumulates, and how circadian rhythms and sleep loss change risk.
Stress
- The Yerkes–Dodson curve: performance rises with arousal to an optimum, then falls; too little arousal causes complacency and too much causes narrowing and overload.
- Acute stress is immediate; chronic stress erodes sleep and judgement. Symptoms include irritability, poor concentration and sleep disturbance.
- Coping strategies include planning, workload sharing and controlled breathing.
Fatigue and sleep
- Fatigue is a physiological state from sleep loss, long duty or circadian disruption; it is not simply tiredness and cannot be overcome by willpower.
- Sleep debt accumulates; recovery requires sleep, not caffeine.
- Circadian low points occur around 0200–0600 and 1400–1600, increasing sleepiness and error risk.
- Sleep inertia immediately after waking degrades performance; allow time before critical tasks.
Worked example
An early departure follows a short night. The pilot is in a circadian low and has sleep debt. The reasonable response is to use available controlled rest if permitted, manage caffeine strategically, and increase monitoring and cross-checks; the risk is not fixed by pushing through.
Traps that cost marks
- Believing caffeine replaces sleep.
- Assuming fatigue only matters on long-haul flights; short early duties can be worse.
- Ignoring sleep inertia after a nap.
- Treating stress as always harmful; optimum arousal is useful.