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

Source: U.S. Department of Transportation, Federal Motor Carrier Safety Administration (FMCSA), December 2012

As part of the Federal Motor Carrier Safety Administration (FMCSA) mandated “Investigation into Motor Carrier Practices to Achieve Optimal Commercial Motor Vehicle (CMV) Driver Performance” Indefinite Date/Indefinite Quantity (IDIQ) Research and Technology Program, a laboratory study was conducted between February 2010 and April 2011 to examine the effect of split sleep versus consolidated sleep on human performance and long-term health-related parameters. This technical report presents the design, methods, research findings, and conclusions of this study.

The study compares the effects of consolidated nighttime sleep, split sleep, and consolidated daytime sleep on total sleep time, performance, participant subjective state, and biomedical parameters. It appears that if consolidated nighttime sleep is not possible, then split sleep is preferable to consolidated daytime sleep. This conclusion is based on the findings of relatively less total sleep time and greater subjective sleepiness in the daytime sleep condition compared to the split sleep and consolidated nighttime sleep conditions. Performance was equivalent across all three of the sleep conditions in the present study. Further, there were some changes in biomedical parameters associated with the different sleep conditions…
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