ACTIVATION FROM ON-CALL DUTY: EFFECT ON PILOTS’ SLEEP, PERFORMANCE, AND FATIGUE

Abstract

INTRODUCTION: Pilots are regularly scheduled for on-call duty. It is unclear whether the uncertainty about an activation from on-call duty will disturb pilots’ sleep, and impair next day performance and alertness. METHODS: We collected data from 31 pilots (26 male, mean age 34 years (7 SD)) during one off-duty period, one day-shift, two early-shifts, and one on-call shift in a sequential design. Pilots recorded their sleep at home with EEG. At the end of each flight duty period (FDP), they performed a 3-min Psychomotor Vigilance Task (PVT) and rated their fatigue. Data were analyzed with mixed ANOVAs and post-hoc adjusted pairwise comparisons. The study was approved by the local ethics committee. Pilots gave written informed consent. RESULTS: Pilots were unexpectedly activated from 19 on-call duties with FDPs starting on average (standard error) at 8:22 am (0:40). In on-call nights, duration spent asleep was 6.4 h (0.4), which was not different from nights before day-shifts (5.8 h (0.2); duty start: 7:21 am (0:10)) and early-shifts (5.6 h (0.1); duty start: 5:54 am (0:03)), both p>0.1), but shorter compared to off-duty nights (7.8 (0.2); p=0.0005). REM sleep was longer in on-call nights (84.6 min (7.8)) compared to nights prior to day- (62.3 min (4.6)) and early-shifts (65.9 min (2.8); both p<0.018), but shorter than in off-duty nights (99.5 min (5.9), p=0.04). Sleep onset latency, sleep efficiency, N3 duration, and number of arousals were not different between nights. PVT median reaction time was longer (217.2 ms (5.2), p=0.03) and fatigue higher (11.8 (0. 6), p<0.001) after on-call nights compared to day-shifts (206.6 ms (2.4), 8.2 (0.4)), but not early-shifts. DISCUSSION: Sleep duration was below the recommended limit value of 7 h for adults before all duty types. Sleep duration and quality during on-call nights were not impaired compared to day shifts. However, performance was slightly decreased and fatigue slightly higher at the end of the FDP. This might be a consequence of the sequential design with on-call duty examined last. LEARNING OBJECTIVES: Sleep before all shifts should be longer. On-call shifts could be scheduled as potential recovery (if not activated) between early-shifts.