Winter study in Finland. Daylight+ testing in the winter darkness of the Arctic Circle

Several hours of driving, then a break, followed by several more hours of driving. The same thing the following day. Sounds tiring? It's what truck drivers do day in and day out. Long-distance drivers above all need to maintain their concentration at all times despite monotonous routes. Added to this, they are frequently on the road in the dark during winter. A winter study conducted in Finland is now shedding some light into the driver's cabin.

Difficult Conditions

Light is extremely important to human well-being. It influences our daily rhythm and determines our physical and mental states. A lack of light can lead to a drop in performance and motivation.

In a truck cab, only a very small fraction of the natural light reaches the eyes of the driver – under 10 percent, in fact. That is why our Development emplouyees are currently focusing on providing additional lighting in the driver's cab.

Test Series and Studies

An initial series of tests enabled them to show already that the additional light made test drivers feel much better. The most recent study delves even further into this finding: does the additional light provided by the Daylight+ system have a positive effect on driver performance? Two specially equipped trucks were sent to Finland in order to find out.

How it Works

The Daylight+ light is mounted in the cab ceiling. Its brightness and color are adjustable. In the morning, the driver is woken by a dawn simulator. During driving, the brightness adjusts to the outside light conditions so that the driver is not dazzled. The luminosity is at its maximum level when the truck is stationary.

The biological effectiveness of the lighting is achieved with a high proportion of blue light of 460-490nm, which activates special receptor cells in the eyes to boost alertness and concentration during the day,

Sebastian Schüler works in the Development department and is doing his doctorate on "Biologically effective light".

Timeline of the Winter Study

The test drives were conducted in two time intervals of four weeks each before and after the turn of the year. The location was Rovaniemi in Finland. The town is situated within the Arctic Circle, where it hardly gets light at all during the day in winter – ideal conditions in which to conduct the study.

The important supporting actors were two Mercedes-Benz Actros trucks with different configurations: whereas one truck had the Daylight+ light fitted, the second truck was equipped with conventional cab lighting.

The leading actors were the truck drivers, of course. Each trucker drove one of the trucks for one working week and then the other truck for another working week. In this way, the study was conducted with eight test subjects over eight weeks of testing. The aim of making drivers change trucks in this way is to analyze individual effects of the light on the respective drivers.

Four aspects are particularly important

  • One of the methods used to measure performance involved a waking EEG.
  • The drivers had to complete a questionnaire at the end of each week to gage acceptance levels.
  • FleetBoard vehicle data was used to monitor driving skills and economy.
  • The level of sleep quality was ascertained by means of questionnaires and light polysomnography on two nights of the week. This method involves analyzing sleep by monitoring several different bodily functions.

Under Observation

Even though everything was documented precisely, the aim was to simulate a real working week as accurately as possible. The truckers therefore drove in the mornings and afternoons as they would on a normal working day, and slept in the truck cab at night for the whole week. They also underwent a whole series of examinations before, during, and after driving, in which the drivers were only ever compared with themselves. In other words, how the performance of an individual driver changes when they receive additional, biologically effective daylight based on clearly defined conditions.

Come ice or snow: the Mercedes-Benz TopFit truck with Daylight+.

Data Upon Data

The results have now been assessed: the adaptive Daylight+ was able to treble the daily dose of light while driving. Together with the light showers before and after a trip, it was possible to increase the light dose received in the cab more than five-fold compared with a normal daily dose. With Daylight+, the brightness in the cab is continually adjusted to the outside conditions by means of a sensor. As a result, the daily light dose can be increased significantly without dazzling the driver.

all of the test subjects were more alert with Daylight+ than in the reference truck without lighting. In terms of minutes, thanks to Daylight+ it was possible to reduce the inattentive period of driving from 44 minutes to 18 minutes on average. Of particular note is the fact that the inattentiveness of the drivers did not increase in the afternoon when the cab was illuminated with Daylight+. As such it was possible to avoid the typical "afternoon slump".

Restful sleep in the cab

However, data were not only recorded while driving, but also at night – to examine sleep quality in particular. The results show that in the week in which the drivers drove the Daylight+ truck, the proportion of deep sleep experienced was higher. More deep sleep means more relaxing sleep, which in turn can result in higher performance.

In short: Daylight+ can enhance safety and comfort

The study provided strong indications that a driver working in conditions "with light" performs better and remains more alert and fitter than in conditions "without light". Thanks to the subjective positive perceptions of the drivers, Daylight+ could also represent a further step towards enhancing road safety.

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