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Chronobiology International







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Controlled Rest (CR) refers to a short, unscheduled, voluntary nap opportunity taken by pilots on the flight deck as a countermeasure to unanticipated fatigue 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 resulting in complete records from 239 flights. Timing of sleep periods and flight schedules were analyzed relative to home-base time. Pearson correlations were used to assess the influence of pilot demographics on CR use. A mixed-effects logistic regression was used to analyze the impact of schedule factors on CR. CR was taken on 46% (n = 110) of flights, with 80% (n = 106/133) of all CR attempts (accounting for multiple CR attempts on 23 flights) estimated by actigraphy to have successfully achieved sleep. Average sleep duration during successful rest periods was estimated as 31.7 ± 12.2 min. CR was more frequent on 2-pilot (69%, n = 83) vs. >2-pilot flights (23%, n = 27); return (60%, n = 71) vs. outbound flights (33%, n = 39); night (55%, n = 76) vs. day flights (34%, n = 34); and (63%, n = 80) vs. >10 h duration flights (27%, n = 30) (all p ≤ 0.001). There was no significant difference for direction of travel (eastbound: 51%, n = 57; westbound: 40%, n = 44; p = .059). Of note, 22% (n = 26) of augmented flights contained both CR and bunk rest. Data from this airline show that CR is most commonly used on flights with 2-pilot crews (duration) and nighttime flights returning to base. Future studies are required to determine the generalizability of these results to other airlines.

Funding Sponsor

Aerospace Medical Association


aviation, countermeasures, fatigue management, Napping, sleep


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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


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