WASHINGTON — An FMCSA-sponsored research brief on the effects of split sleep schedules on commercial vehicle driver safety and health appears to cast somewhat of a pall over the Federal Motor Carrier Safety Administration’s reasoning for requiring eight consecutive hours in the sleeper berth.
It also seems to support truck drivers’ claims that they can operate safely with a different rest regulation than is now in place, one that would give them the opportunity to split sleeper berth time into two periods of their choosing with less rigid standards in place rather than requiring them to spend eight consecutive hours in the sleeper berth.
The study, conducted by renowned sleep expert Dr. Greg Belenky of the Sleep and Performance Research Center at Washington State University, concluded that performance was not significantly affected by sleep opportunity placement, whether it be consolidated daytime sleep, consolidated nighttime sleep or split sleep.
And, the study suggested that when consolidated nighttime sleep is not possible, split sleep is preferable to consolidated daytime sleep.
Many drivers had hoped the new Hours of Service rule scheduled to go into effect July 1 would return the sleeper berth rule to its pre-2005 form when they could split the sleeper berth time into two periods provided neither was less than two hours.
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The FMCSA said the 2005 requirement was implemented because studies showed that drivers are less likely to be fatigued if they take a single eight-hour block of rest than if they break their rest into smaller periods of time as they were allowed under the previous rule.
FMCSA Administration Anne Ferro had promised the agency would revisit the sleeper berth issue, but whether the just-released research study will be the catalyst to a change remains to be seen.
The study was designed to determine whether split sleep was as beneficial as consolidated sleep with respect to sustaining driver safety and operational performance and, over the long term, with respect to sustaining driver health.
It was an in-residence laboratory study conducted from January 2010 to May 2011.
Three sleep conditions were examined: consolidated nighttime sleep, split sleep and consolidated daytime sleep.
Fifty-three participants, divided among the three conditions, were studied in the laboratory for nine days, which included two baseline days, a five-day simulated workweek and a two-day recovery period with the core of the study being the five-day work week.
All three sleep conditions had the same total sleep opportunity of 10 hours per day —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 slept, ate, took performance tests and had blood draws within the confines of the sleep laboratory.
Participants had no contact with the outside world (no cell phones, e-mail, visitors, live television, radio, or Internet).
The participants in this study were young men (age range 22–40 years), healthy, and non-obese (body mass index less than 30) in order to reduce the possibility of random factors affecting the data.
Thus, the study population and the study environment were purposely not representative of the population of CMV drivers and their normal working environment, the research report said.
If a difference had been found in the laboratory setting between split and consolidated sleep, then the expectation was that these findings would be followed up with a field study using drivers in their usual environment driving their usual revenue-producing routes.
The study population in such a field study would be chosen to be more representative of the industry and would therefore be persons who were older, heavier, include women, and generally more heterogeneous.
A spokesman for the FMCSA said no field study was planned as a follow-up to the lab study.
During the five-day simulated work week, participants in the nighttime sleep condition slept the most (total sleep time per day 8.4 hours plus or minus 13.4 minutes standard error of the mean) followed by participants in the split sleep condition (total sleep time per day 7.2 hours plus or minus 14.2 minutes). Participants in the daytime sleep condition slept the least (total sleep time per day 6.4 hours, plus or minus 15.3 minutes).
The researchers said the results of the study suggest that when consolidated nighttime sleep is not possible, split sleep is preferable to consolidated daytime sleep.
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