BACKGROUND: Working night shift (reverse cycle) presents problems to personnel due to the difficulty in maintaining alertness during the nighttime hours. When the shift must be worked several consecutive nights, a cumulative sleep debt is created. Appropriate countermeasures are required to help personnel obtain as much sleep as possible so they may perform their duties effectively.
HYPOTHESIS: The objectives were to determine whether a hypnotic taken before daytime sleep would improve sleep quality, and to determine whether improved daytime sleep would increase alertness, reduce fatigue, and mitigate the usual performance decrements which occur on night shift.
METHODS: Sixteen UH-60 Army aviators were randomly assigned to either a temazepam or a placebo group. Test sessions, consisting of vigilance assessments, flight simulation, and mood state questionnaires were administered during baseline, three nights of reverse cycle, and three days following a return to day shift. Temazepam (30 mg) was administered before daytime sleep to one group while another group received a lactose-filled capsule.
RESULTS: Subjects who received temazepam slept longer and with less fragmentation than those who received placebo. Generally, the subjects in the temazepam group indicated more subjective alertness and less fatigue than those in the placebo group. Flight performance was not unequivocally improved by better daytime sleep, but the temazepam group performed better on the Psychomotor Vigilance Task than the placebo group.
CONCLUSIONS: Temazepam is helpful in prolonging daytime sleep, with some attenuation of performance decrements during the night shift. However, physicians should be careful when administering this substance to ensure the aviator has a minimum of 8 h in which to sleep.
