Feeling sleepy behind the wheel? A blast of cold air will help

Research shows six minutes of cooling makes tired drivers more alert

By Elisabeth Schmidt

Have you ever felt your eyelids begin to close as the monotonous sounds and vibrations of the highway lull you into a relaxed state? This is a serious safety concern for vehicles on motorways, and will become increasingly important as we drive in more automated vehicles. So what’s the best way to overcome the fatigue?

According to our recent research – a collaboration between BMW AG and Technical University Chemnitz – a blast of cold air could be all it takes to wake you up again. Armed with this information, we can design features in cars that track how the driver is feeling and help make them more alert – and therefore safer.

For our new study in Applied Ergonomics, we used a driving simulator to compare how sleepy car drivers were with and without cold air. We asked 34 people (who were not sleep deprived) to drive a car along a monotonous highway for 26 minutes. By doing this, we were inducing what’s called “passive fatigue” – tiredness due to having too little to concentrate on (“task underload”).

They drove the simulation twice: once with no intervention, and once with a six-minute blast of cold air at the end of the drive. We recorded certain measurements during and after the drives to determine and rank how sleepy they were feeling.

We found that with the cooling, drivers were significantly less sleepy; their pupils got wider and their skin more conductive, both of which indicate arousal. We also noticed an improvement in driving performance and a decrease in blinking.

Taken together, the results suggest that cold air directed towards the driver reduces the driver’s feeling of passive fatigue and increases their physiological arousal for a few minutes, essentially making them more alert.

  • A growing problem

Driver fatigue is not only uncomfortable for the driver but it’s also an important issue for traffic safety. Sleepy drivers are six times more likely to crash or nearly crash than awake drivers. For this reason, driving while sleepy is a problem to the public.

As our cars take over more and more of our driving tasks, like staying in lane, maintaining speed and avoiding crashes, our risk of passive fatigue is likely to increase. In the future, when vehicles can fully self-drive, this may become less important (and we might even be comfortably sleeping behind the wheel), but in semi-automated vehicles it is a real – and growing – concern.

Research efforts towards improving in-car sleepiness detection and exploring methods to mitigate fatigue are hence of interest. Appropriate methods to manage fatigue will positively affect drivers’ comfort and potentially mitigate the risk of accidents.

Sleepiness sensors

One of the big trends today is the “quantified self” – measuring our physical responses, like heart rate and movement. This is the result of sensor technologies reaching a degree of maturity that allows individuals to track their physiological and behavioral data with simple devices such as wristbands. Such devices are already popular for monitoring people’s fitness and activity, and the progress in sensor technology will also enable us to track drivers’ states while driving.

Having this kind of data available while driving allows for real-time countermeasures: upon detection of a driver’s sleepiness, the device could alert the vehicle to blast cold air through the vents. We now need lab and field studies to understand the effectiveness of countermeasures such as sensory stimulation and to investigate their impact.

Our research shows that thermal stimulation can reduce the sleepiness that arises from a monotonous driving task and activate the driver for a short amount of time. This shows that sensory stimulation has the potential to mitigate driver fatigue that arises from task underload. It also becomes clear that there is a lot left to learn about possibilities to lengthen the effect. I am interested in researching ways of activating tired drivers that are both pleasant and effective, which I hope will contribute to safer driving in the future.

About the author

Elisabeth Schmidt obtained her BSc and MSc in mechanical engineering from the Technical University of Munich, focusing on motor vehicle technology. She spent a part of her master’s studies at the Massachusetts Institute of Technology to research methods in product development processes.

Now she is working towards her doctoral degree in cooperation with BMW and the Department of Ergonomics and Innovation Management at Chemnitz University of Technology. Her thesis deals with methods for managing driver fatigue with a focus on thermal stimulation.