Schedule Factors Associated with the Use of Controlled Rest in a Long-Haul Airline

Controlled Rest (CR) refers to a short, voluntary nap opportunity taken by pilots on the flight deck as a countermeasure to unanticipated sleepiness in flight. This study explores the profile of CR use in a long-haul commercial airline. Forty-four pilots wore actiwatches and filled in an application-based sleep/work diary for approximately 2 weeks. After merging sleep diary, actigraphy, and schedule data, complete records were analyzed from 240 flights. Sleep was estimated during CR intervals using the Philips Actiware 6.0.9 (Bend, OR) software with wake threshold set to medium. Timing of sleep periods and flight schedules were analyzed relative to home-base time. A mixed-effects binary logistics regression was used to analyze the impact of schedule factors on CR. Preliminary analyses revealed that CR was taken on 45% (n=107) of flights. Average sleep duration within these rest periods was estimated as 24.8 ± 16.1 minutes. CR was more frequent on return flights (arriving at home-base; 58%, n=69) vs. outbound flights (departing from home-base, 31%, n=38; p<0.001). There was no difference for direction of travel (eastbound: 49%, n= 56; westbound: 40%, n= 44; northbound/southbound: 50%, n=7; p=0.272). CR was more frequent on 2-pilot flights (62%, n=81) compared to augmented crew flights (24%, n=26; p<0.001). Of note, 21% (n=23) of augmented flights contained both CR and Bunk Rest. CR was more frequent on flights <10h duration (<10h: 59%, n=78; >10h: 27%, n=29; p<0.001). Flights departing between 12:00h-19:59h (25%, n=23; p<0.026) had the lowest frequency of CR. Data from this airline show that CR is most commonly used as a countermeasure to sleepiness on return, unaugmented, <10h duration, and nighttime flights. The direction of travel did not influence the use of CR. Future studies are required to determine generalizability of these results to other airlines.