Research Finds No Difference Between Split Sleep and Continuous Sleep

New research may force a revision in thinking about sleep requirements for professions like long-haul truckers and airline flight crews.  The study, conducted at the Washington State University, shows there’s no difference between utilizing a split sleep schedule and a continuous sleep schedule.

The researchers brought 53 participants to the university’s Sleep and Performance Research Center for nine days.  During their stay at the center, the subjects simulated a five day workweek, with two baseline days before and two recovery days after.  Participants were split into three sleep conditions — consolidated nighttime sleep (10 p.m.–8 a.m.), split sleep (3 a.m.–8 a.m. and 3 p.m.–8 p.m.), and consolidated daytime sleep (10 a.m.–8 p.m.).

During the study, participants had no contact with the outside world (no cell phones, email, visitors, live television, radio, or Internet).

Performance was measured by a variety of tests throughout the study. A driving simulator allowed participants drove a 40-minute route while being closely monitored. Participants also took a 10-minute reaction time test and a performance test involving matching numbers to symbols.

The study found the participants in the daytime consolidated sleep received less total sleep time and experienced increased sleepiness and an increase in blood glucose and testosterone at the end of the workweek. However, performance was not significantly affected by the schedule during which the participants sleep.  Results of this study suggest that when consolidated nighttime sleep is not possible, split sleep is preferable to consolidated daytime sleep.

Source: Research brief