EVALUATING THE SENSITIVITY OF SLEEP MEASURES FOR MONITORING PILOT FATIGUE IN OPERATIONAL SETTINGS

Abstract Introduction Previously, combined data analyses of four pilot fatigue monitoring studies including 237 pilots flying long-haul and ultra-long range (ULR) flights found no association between pilots’ actigraphic sleep in flight and psychomotor vigilance task (PVT) performance at top-of-descent (TOD; beginning of the landing phase of flight). The present study aimed to determine whether measures of in-flight sleep recorded with polysomnography (PSG) are more sensitive predictors of pilots’ PVT performance near TOD than actigraphic measures. Methods Data were re-analysed from 41 Singapore Airlines A340-500 pilots (median age 47, range 29–58 years) monitored on a ULR trip between Singapore and Los Angeles (average flight duration outbound = 15.6 hrs; inbound = 17.2 hrs). In-flight sleep was recorded simultaneously with PSG (scored in 30-second epochs) and actigraphy (recorded in 30-second epochs and scored in conjunction with sleep diary information). PSG- and actigraphy-determined time awake were calculated as the duration between the end of the last epoch scored as sleep (PSG) or software-scored sleep interval (actigraphy) and the start time of the 10-minute PVT completed near TOD. Results Linear mixed modelling indicated that after controlling for flight sector and intra- and inter-individual variability, neither PSG-derived total in-flight sleep (F (1, 44.4) = 0.006, p= 0.941) and time awake (F (1, 34.3) = 0.431, p= 0.516), nor actigraphic total in-flight sleep (F (1, 51.1) = 0.161, p= 0.69) and time awake (F (1, 34.9) = 0.23, p= 0.634) were associated with PVT response speed at TOD. Conclusion In this context, actigraphy produced identical findings to polysomnography and remains a valid alternative for monitoring in-flight sleep of groups of pilots during ULR flights. Further research is needed to determine whether PVT performance is a discriminatory measure of fatigue-related impairment in pilots. Support This analysis was supported by the Massey University College of Health Research Fund. The Singapore Airlines study was funded by the Singapore Civil Aviation Authority. We thank Dr Jarnail Singh for permission to use these data.