2013 Volume 89 Issue 5 Pages 174-194
We conducted a preliminary field study that examined sleep-wake rhythms and on-board performance in simulated airline pilot crew systems in two international west bound Narita-Delhi and Fukuoka-Mumbai flights. The out- and home-bound Delhi flights were conducted as nighttime operations with the single crew system, and the out-bound flight from Mumbai as a daytime operation and the home-bound flight as a night flight with the multiple crew system. Two male researchers (age 36 and 47) participated in this investigation acting as a captain and a first officer. Changes in Psychomotor Vigilance Task (PVT) performance during the flight operations as well as sleep-EEG and rectal temperature at all the sleep periods were measured. The sleep duration during the first layover night just after the out-bound flights was shorter than the daily nighttime sleep duration in Japan. Due to constraints of the earlier departure time at Mumbai, the duration of a prophylactic nap taken just before the home-bound flight was shorter than that taken at Delhi. Sleep architecture of a middle-aged participant was more impaired than that of a younger participant. The PVT performance thus reflected the negative impact by the night-time flights compared with the daytime flights, and the negative impact by the home-bound flights compared with the out-bound flights. Daytime napping (the replacement nap) on the layover day facilitated the increase in the duration of main sleep at local time. The home-bound flights at nighttime operations were associated with considerably higher levels of PVT lapses than the out-bound flights, but the observed impairments were mitigated by on-board napping. These results suggest that it will be important to take on-board napping, particularly for a middle-aged captain, and we would like to reflect these findings in the next investigation.