SLEEP AND WAKE PATTERNS IN AIRCREW ON A 2-DAY LAYOVER ON WESTWARD LONG-DISTANCE FLIGHTS

Background: As part of a research program of sleep/wake disturbances i n connection with irregular work hours and time zone transitions, the study aimed to describe the spontaneous sleep/wake pattern in connecti on with a westward (Stockholm to Los Angeles) transmeridian flight (-9 h) and short layover (50 h). Hypothesis: To describe all sleep episod es and the recovery process across 4 d, and to relate adjustment to in dividual differences. Methods: We monitored 42 SAS aircrew for 9 d wit h activity monitors and diary before, during, and after flight. Result s: During the outbound day the wake span was 21.7 h and 90% of the air crew adopted local bed times on layover. The readaptation to normal sl eep/wake patterns were rapid on the return. Napping was common (93%), especially on-board and before the return. Sleep efficiency dropped be low 90% during layover, being fell to be too short and disturbed by aw akenings, and gradually returned to normal across four recovery days. Recovery sleep was characterized by difficulties waking up and feeling s of not being refreshed from sleep. Sleepiness symptoms increased dur ing layover and gradually decreased across recovery days, still being elevated on day 4. Conclusions: In the present study we found that wes tward nights are associated with extended wake spans during layover, i ncreased sleepiness, and slow recovery on return home. Strategic sleep ing may counteract the effect somewhat, but individual differences are few.