Investigation of the Effects of Split Sleep Schedules on Commercial Vehcle Driver Safety and Health

https://doi.org/10.21949/15027262012PDFTech ReportFMCSA-RRR-12-003DriversFatigue (Physiological condition)Human factors in crashesResearch HubUnited StatesUnited States. Federal Motor Carrier Safety AdministrationUnited States. Federal Motor Carrier Safety Administration. Technology DivisionUnited States Federal Motor Carrier Safety AdministrationThe objective of this study was to evaluate the consequences for safety and health of split sleep versus consolidated sleep by comparing the effects of consolidated nighttime sleep, split sleep, and consolidated daytime sleep on total sleep time, performance, subjective state, and biomedical measures that correlate with health outcomes over the long term. An in-residence laboratory study was conducted on 53 healthy participants making a between-group comparison of nighttime, split, or daytime sleep across a 5-day simulated workweek. The effect of the three sleep conditions was measured on sleep by polysomnography (PSG), performance by the psychomotor vigilance task (PVT), high fidelity driving simulator, digit-symbol substitution task (DSST), and subjective state, as well as the long-term health-related biomedical measurements of blood glucose, interleukin 6 (IL-6), leptin, testosterone, and blood pressure (BP). In comparison to consolidated nighttime sleep or split sleep, participants in the daytime sleep condition slept less and were subjectively sleepier. While performance, mood, and BP were unaffected by sleep condition, there were elevations in glucose and testosterone in the daytime sleep condition at the end of the workweek. With respect to total sleep time and sleepiness, the findings of the present study suggest that split sleep is preferable to consolidated daytime sleep. This finding has implications for any revision of the Federal Motor Carrier Safety Administration (FMCSA) rules governing sleeper berth use in commercial motor vehicle (CMV) drivers93