Sleep in Airplanes: Potential risk factors

Abstract

Sleeping in airplanes implies sleeping under hypobaric conditions. At cruising altitude the cabin pressure equals an altitude of 8000 ft. Little is known of the physiological effects for crew and passengers. At the DLR-Institute of Aerospace Medicine, 16 healthy subjects (8 female), average age 28 years (± 4 SD), slept in a pressure chamber furnished as crew-rest-compartment during a realistic flight simulation concerning atmospheric conditions and noise. Blood oxygen saturation (SpO2), heart rate, and Sleep-EEG were recorded during the 4h sleep period. The next morning performance was tested using an unstable tracking task reflecting typical operator demands. A control group of 16 subjects (8 female), average age 26 years (± 6 SD), slept 4h in private sleeping rooms of the DLR-isolation unit in normobaric conditions. SpO2 and heart rate differed significantly between groups (p<0.0001). During time in bed a mean SpO2 level of 96% (± 1 SD) and a mean heart rate of 62 bpm (± 8 SD) were measured under normobaric conditions, whereas mean SpO2 level in the pressure chamber was 88% (± 1 SD) with a mean heart rate of 74 bpm (± 6 SD). Under hypobaric conditions the average SpO2 dropped below 90% for 135 min (± 69 SD) and the mean minimum SpO2-level was 81% (± 3 SD). Performance was significantly more impaired in the experimental group (p<0.05). The recuperative function for crew members sleeping in a crew-rest-compartment during flight seems limited since performance is impaired and SpO2 drops considerably. Sleep aboard an airplane induced hypobaric hypoxia in young, healthy subjects. To date, the degree of arterial hypoxemia that should be considered as being harmful remains unclear. However, passengers with a SpO2 below 85% in the hypoxic challenge test are recommended to receive supplemental oxygen during flight. Consequently, for risk groups sleep during flight should be regarded with care