Does the biological effect of light have a positive influence on the well-being and performance of truck drivers? A research team from Daimler has been exploring this interesting question in the darkness of Finland’s polar night.
A total of eight Daimler test drivers simulated two typical working weeks for truckers at the site in Rovaniemi. The truckers alternated between driving for one week in a truck cab with conventional lighting and for another week in a cab with a Daylight+ module that provides additional daylight while driving and during breaks.
In order to ascertain the possible benefits of applying daylight inside the truck cab, project manager and head of the experiment, Siegfried Rothe from the Daimler research department, defined the following statement as a working hypothesis: that an application of biologically effective light with a wavelength of between 460 and 490 nanometres has positive effects. He designed a sophisticated series of experiments in order to obtain valid results.
Light gives structure
For many years, scientists have been researching the complex relationships between the availability of biologically effective light and the physical and mental states of human beings.
Various related health problems have been defined. One of the most common is seasonal affective disorder (SAD). A lack of light is a serious problem for many people in the countries of Northern Europe, for example, where it barely gets light during the winter months and which can result in poor mood, reduced performance and a lack of motivation. Light therapy is a standard method of treating these symptoms medically and of successfully combating them.
Drivers compared against themselves
Siegfried determined that, due primarily to the outline shape of a conventional truck cab, only a comparatively low percentage of natural daylight reaches the driver’s light receptors. This finding prompted him to think about potential solutions.
The results of an initial series of experiments with engineers from the test drive department were unambiguous. The subjective condition of all test subjects improved significantly under the influence of an additional dose of light, regardless of the time of day. Another finding proved surprising: the test drivers with more daylight in the cab drove more economically.
During the experiments in Rovaniemi, the test subjects were only ever compared against themselves. That is, the experiments examined how a driver’s performance changes when they were exposed to additional biologically effective daylight under clearly defined conditions. The extra dose took three forms involving different intensities:
- Steady light while driving, whereby the intensity was adjusted to the exterior light level.
- An intense light shower of maximum intensity during the tests, before and after driving.
- Light during breaks while the driver relaxes in their seat, which has been positioned for a power nap.
Mental state and professional performance, which are closely related, were examined using standardised psychological test procedures (sustained attention and reaction tests on the computer) and by recording vehicle data through the FleetBoard telematics system.
At the end of the two-week cycles, the individual drivers were interviewed, having previously recorded their subjective impressions. The drivers consistently reported that they perceived the space inside the cab to be considerably more pleasant with an additional light fitting.
“When designing the series of tests, we hadn’t even considered that the space might appear larger.” Siegfried estimates that it will take several months to sift and analyse the extensive data from the series of experiments conducted in the Arctic Circle. “Only then we will be able to make a recommendation as to whether the test findings should advisably lead to changes in the design of cab lighting,” he concludes.
Mercedes-Benz South Africa, m.mercedes-benz.co.za