Today’s blog was submitted By Pete Johnson, Ph.D., MS, Professor Emeritus, University of Washington. Dr. Johnson is a member of an Oregon Healthy Workforce Center research team. The featured photo is of research team member, Jason Malach-Fuller, placing an accelerometer on a truck sleeper berth mattress.
Oregon Health & Science University and the University of Washington have completed studies on team truck drivers’ sleep, health, and well-being (Tech4Rest study). Main study goals were to determine whether there were differences in whole-body vibration exposures, sleep, and health when the truck driving teams used an innerspring mattress (the industry standard mattress) and a therapeutic mattress. The therapeutic mattress was made of interlocking foam of different densities based on body region, and included a novel suspension support system. Team truck driving is a challenging work environment where one team member drives while the other team member tries to relax or sleep in the sleeper berth of the truck cab.
The studies revealed:
- There were small differences between the mattresses in the vibrations experienced by the mattress occupants.
- The unexpected factor creating the largest difference in vibration transmission through the mattresses was the type of tires on the truck.
- Compared to the standard innerspring mattress, the therapeutic mattress produced small increases in sleep duration but medium-to-large improvements in reported sleep quality and fatigue
- All 16 truck drivers preferred the therapeutic mattress.
- There was no way to link the vibration differences to the overwhelming preference for the therapeutic mattress.
These benefits are encouraging. However, the therapeutic mattress may be a tough sell in most commercial team truck driving companies because it costs substantially more than the industry standard innerspring mattress, and mattresses have to be replaced whenever drivers leave (turnover is frequent). However, longer-term, owner-operator teams may benefit from their mattress investment.
Other findings raised new questions. Typically, semi-trucks have dual tires on their rear axles. A new tire option to improve gas mileage consists of replacing the dual tires on the rear axles with one larger, heavier, higher pressure tire called a “super single”. Surprisingly, the truck tires had the greatest impact on the vibration levels measures in the truck cab. The “super single” tires transmitted more vibration to the sleeping driver.
This is an example of how research designed to answer one question (vibration-related differences in sleep quality between mattresses) creates new questions for future research (vibration-related differences between trucks due to new types of tires). A future challenge would be to determine how the fuel savings from the super single tires compares to the potential sleep, health, and economic impact of the higher vibration levels experienced by the occupants in the truck cab.
Acknowledgements: This research received funding from the Oregon Healthy Workforce Center, a National Institute for Occupational Safety & Health Center of Excellence in Total Worker Health® (grant number U19OH010154, Leslie Hammer and Ryan Olson MPIs). This work was also supported by a Safety and Health Improvement Project grant from the State of Washington (grant number 2014YH00280, Pete Johnson and Ryan Olson MPIs), and the Oregon Institute of Occupational Health Sciences via funds from the Division of Consumer and Business Services of the State of Oregon (ORS 656.630).
Learn more about the Oregon Healthy Workforce Center and the Tech4Rest study. The Oregon Healthy Workforce Center (OHWC) was funded in September 2011 as a NIOSH Total Worker Health Center of Excellence (Grant: NIOSH U19OH0101). OHWC faculty and staff come from various backgrounds and expertise in occupational health psychology, industrial organizational psychology, industrial hygiene, physiology, public health, communications, and engineering.