Comparison of the effects of zolpidem-induced prophylactic naps to placebo naps and forced rest periods in prolonged work schedules.

The efficacy of zolpidem-induced prophylactic naps was compared to placebo naps and forced-rest periods for sustaining alertness. Eighteen subjects were exposed to three separate 38-hour periods of continuous wakefulness, each separated by 10 hours of recovery sleep. Three conditions were used: a 2-hour evening nap (at 2100 hours) induced with 10 mg zolpidem tartrate; a 2-hour nap (at 2100 hours) with placebo; and a 2-hour rest break with no sleep. Following the naps or rest period, subjects remained awake for 23 additional hours. A VAS was administered at 1-hour intervals, RTSWs and POMS were administered at 2-hour intervals, and a cognitive task was completed at 4-hour intervals. Results indicated the effectiveness of prophylactic naps for sustaining mood, alertness, and performance throughout the final 23 hours of a 39-hour period of sustained operations. Both napping conditions attenuated the decrements normally associated with total sleep deprivation, but the zolpidem nap was the most effective because subjects obtained the most sleep after zolpidem administration. Postnap grogginess persisted for about 2 hours after either the zolpidem or placebo nap, a fact which, despite the overall benefits from prophylactic naps, could compromise performance under operational conditions if insufficient time for awakening is planned.