Short Rest Between Flights Is Associated With Increased Serum Stress Hormone Levels in Airline Pilots: A Cross-Sectional Study

Abstract

Background: Work-related stress is a critical area of research in civil aviation, given the potential for severe consequences when airline pilots (APs) are overwhelmed or unable to perform optimally. While pilots are traditionally considered to be exposed to various stressors, the impact of specific occupational characteristics on stress in the aviation industry remains inadequately understood. Considering that biomarkers are increasingly being utilized as objective measures of stress in human research, this cross-sectional study investigated the association between occupational variables and serum levels of cortisol and dehydroepiandrosterone sulfate (DHEAS) as stress biomarkers in commercial APs. Methods: A total of 120 male APs completed a survey assessing the following work-related characteristics: position (captain vs. first officer), years of experience, total flight hours, flight hours in the preceding year, inter-flight rest duration, and flight route length. Serum cortisol and DHEAS concentrations were determined from venous blood samples obtained between 08:00 and 09:00 a.m., following a minimum eight-hour fasting period. The biomarker data were analyzed in relation to the aforementioned occupational characteristics. Results: The mean serum cortisol and DHEAS concentrations in the entire cohort were 8.5±2.1 µg/dL and 214.6±96.4 µg/dL, respectively. There were no significant differences in the levels of the two stress hormones in relation to position, years of experience, total flight hours, flight hours in the preceding year, or flight route length. However, an inter-flight rest period of less than one hour was significantly associated with elevated serum cortisol (P<0.01) and reduced DHEAS levels (P<0.001) compared to longer rest durations. Notably, a stepwise decrease in DHEAS concentrations was observed for rest periods of <1 hour, 1-4 hours, 4-24 hours, and >24 hours. After adjustment for potential confounders in multivariable analyses, a rest period of <1 hour remained independently associated with both serum cortisol (odds ratio [OR]=1.09, 95% confidence interval [CI]=1.04-1.13, P<0.01) and DHEAS (OR=0.94, 95% CI=0.92-0.97, P<0.001). Conclusions: Serum stress hormones in APs are associated with short inter-flight rest periods. Optimization of rest durations may contribute to improved pilot well-being and performance. Further research is warranted to determine ideal rest period lengths and develop interventions to mitigate the potential adverse effects of abbreviated rest periods between flights.