Sleep Disordered Breathing(SBD) is a common disorder that is becoming more recognized in the active duty military population. A major consequence of SDB is excessive daytime sleepiness(EDS). The maintenance of wakefulness test(MWT) is a daytime polysomnography(PSG) performed after nighttime PSG that has been used to evaluate EDS. It can assess an individual’s tendency to fall asleep which has important military relevance for those soldiers whose duties include guard duty as well as operating heavy machinery and driving military vehicles. We conducted consecutive MWTs on active duty soldiers diagnosed with mild to moderate Obstructive Sleep Apnea(OSA) and Upper Airway Resistance Syndrome(UARS) to evaluate their tendency to fall asleep.
Active duty soldiers referred to the BAMC Sleep Disorders Center between February 2004 and March 2005 who were evaluated with an overnight PSG and had an apnea-hypopnea index(AHI) greater than 5/hr and less than 30/hr were defined as having OSA in the mild or moderate range. Soldiers with EDS and an AHI less than 5/hr but a respiratory disturbance index(RDI) of >5/hr were defined as UARS. After overnight PSG, soldiers with mild to moderate OSA and UARS were evaluated with a 40 minute protocol MWT. Sleep during the MWT was defined as three consecutive epochs of stage one or one epoch of any other stage of sleep. Abnormal MWT was defined as a sleep onset latency mean of the 4 sessions below 35 minutes.
Sixty-nine soldiers met entry criteria. Thirty-nine percent(39%) were diagnosed with UARS and 61% of soldiers with OSA. This subjective excessive sleepiness was confirmed with a mean MWT sleep onset latency of 27 minutes. Fifty-two percent of soldiers had abnormal MWTs.
Patients with untreated SDB who have excessive daytime sleepiness could pose a problem in the military work environment where wakefulness and attentiveness are essential for both job performance and mission accomplishment.
Soldiers with UARS and mild to moderate OSA should not be deployed into situations where alertness is required for personal and unit safety.
Christopher Powers, None.