In-flight sleep of flight crew during a 7-hour rest break: implications for research and flight safety.

STUDY OBJECTIVES

To assess the amount and quality of sleep that flight crew are able to obtain during flight, and identify factors that influence the sleep obtained.

DESIGN

Flight crew operating flights between Everett, WA, USA and Asia had their sleep recorded polysomnographically for 1 night in a layover hotel and during a 7-h in-flight rest opportunity on flights averaging 15.7 h.

SETTING

Layover hotel and in-flight crew rest facilities onboard the Boeing 777-200ER aircraft.

PARTICIPANTS

Twenty-one male flight crew (11 Captains, mean age 48 yr and 10 First Officers, mean age 35 yr).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Sleep was recorded using actigraphy during the entire tour of duty, and polysomnographically in a layover hotel and during the flight. Mixed model analysis of covariance was used to determine the factors affecting in-flight sleep. In-flight sleep was less efficient (70% vs. 88%), with more nonrapid eye movement Stage 1/Stage 2 and more frequent awakenings per h (7.7/h vs. 4.6/h) than sleep in the layover hotel. In-flight sleep included very little slow wave sleep (median 0.5%). Less time was spent trying to sleep and less sleep was obtained when sleep opportunities occurred during the first half of the flight. Multivariate analyses suggest age is the most consistent factor affecting in-flight sleep duration and quality.

CONCLUSIONS

This study confirms that even during long sleep opportunities, in-flight sleep is of poorer quality than sleep on the ground. With longer flight times, the quality and recuperative value of in-flight sleep is increasingly important for flight safety. Because the age limit for flight crew is being challenged, the consequences of age adversely affecting sleep quantity and quality need to be evaluated.