Excessive daytime sleepiness in a trainee military pilot.

A 21-yr-old army trainee pilot was noted by his colleagues to be frequently falling asleep in his class and was reported to medical authorities. Despite a number of investigations and review by two sleep specialists, a formal diagnosis could not be made. During his medical review board three questions were posed: does the trainee have excessive daytime sleepiness (EDS), or is his sleepiness a variation of normal; if he is excessively sleepy, what is the most likely diagnosis; and should the trainee be allowed to continue to undertake pilot training based on most likely diagnosis and/or his history. The most likely diagnosis was considered to be idiopathic hypersomnia, a relatively uncommon condition which is a diagnosis of exclusion. The condition was considered incompatible with flight duties in a pilot under training due to the potential for compromise of performance, mission completion, and flight safety. Stimulant medications may control symptoms, but are incompatible with flying duties in the Australian Defense Force. This case illustrates the difficulties in determining aeromedical disposition in borderline cases of EDS where a clear diagnosis cannot be made.