The Maintenance of Wakefulness Test as a Predictor of Alertness in Aircrew Members with Idiopathic Hypersomnia

Aviators are required to maintain a high level of alertness during their missions. Two conditions that may disrupt this alertness are fatigue and hypersomnia. Fatigue is a physiological state, while hypersomnia is a pathologic state, also termed excessive daytime sleepiness (EDS), which is manifested by the tendency to fall asleep in inappropriate places or situations, such as during flight or driving. Hypersomnolence may be diagnosed by subjective measurements, such as the Epworth sleepiness scale, but the diagnosis is established by two objective tests: the Multiple Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test (MWT). The first consists of four 20-min sessions used to determine the time it takes the patient to fall asleep when given the opportunity and is considered positive when the sleep latency time is shorter than 5 min, although some authors use 8 min as the cut-off for the diagnosis. The Maintenance of Wakefulness Test (MWT) consists of four 40-min sessions during which the patient attempts to maintain wakefulness while seated in a dark, quiet room during the day. Herein we report 2 cases of aviators who were returned to flying duty despite a pathologic MSLT. These aviators were waivered based on a normal MWT and safety history obtained from their commanders.