Fatigue is an insidious threat to aviation safety because of the impairments in alertness and performance it creates. The fatigue associated with sleep loss, shift work, and long duty cycles can cause aviators to become sloppy, inattentive, careless, and inefficient. The only cure for fatigue is adequate sleep; however, gaining sufficient amounts of sleep is often difficult because of work requirements, family demands, or poor sleep habits. Although it may not be possible to avoid some of these problems, pilots can improve their sleep habits and thus gain more restful and restorative sleep by using self-administered relaxation therapy, establishing consistent and soothing bedtime routines, and avoiding certain activities and substances immediately prior to sleep. When opportunities for adequate sleep are not available because of work-related factors, prophylactic naps can sustain performance until sleep is possible.