Many aspects of Shuttle missions may have significant impact on the normal sleeping patterns of crewmembers. Using a standard debriefing form, 58 crewmembers from 9 Shuttle flights (6 single-shift flights, and 3 dual-shift flights) were debriefed within 3 d postflight. Specific questions on the form relating to sleep quality and quantity, fatigue, and sleep medication usage during all flight phases were analyzed. Of crewmembers on dual-shift missions 50% (11 of 22) used sleep medications at least once inflight compared to 19.4% (7 of 36) of single-shift. The biggest impact on normal sleep patterns occurred during the first and last days of a mission, with averages of 5.7 h and 5.6 h, respectively. These results suggest that sleep disruption is a common occurrence on Shuttle missions. Further studies are suggested to develop strategies for coping with this potential problem.