Sleep patterns in aircrew operating on the polar route between Germany and east Asia.

The study was performed as the second part of an investigation to assess sleep behavior and circadian rhythmicity in aircrew operating regular passenger flights between Germany and East Asia via Anchorage (ANC). Continuous records of sleep and ratings of sleep quality were obtained by sleep logs from 101 B747-cockpit crewmembers, starting at least 3 d before commencing flight duty, continuing during days on duty (the duration depending on the flight schedule) and finishing 4 d after return, at the earliest. Regardless of the specific duty roster, sleep deficit occurred mainly after the first flight leg to ANC, presumably due to the 10-h time zone difference and the short layover time. During the layover in the Far East, the sleep deficit diminished partly because of additional naps. Sleep was often disturbed and scattered over days and nights. Another pronounced sleep deficit occurred after the first return flight from South Korea or Japan to ANC. Compared to the outgoing layover period in ANC, the number and duration of naps increased during this layover and, additionally, on the first 2 d after returning home. Poorer sleep quality ratings were associated with accumulated sleep deficit and increased napping, but significant decrements in sleep quality were seen only during two out of the six different duty rosters. All six of the polar route duty rosters may lead to significant sleep disturbances. During some flight schedules the sleep deficit is large enough to raise operational implications.