written by the home doctor team

Australian study explains why you feel tired behind the wheel

A new Australian study has found a car’s vibrations make people sleepier, affecting concentration and alertness levels just 15 minutes after drivers get behind the wheel.

Professor Stephen Robinson said the effects of physical vibration on drivers were not well understood, despite growing evidence that vibration contributes to feelings of sleepiness.

“We know one in five Australians have fallen asleep at the wheel and we know that drowsy driving is a significant issue for road safety,” Robinson said.

What did the study involve?

Researchers from the Royal Melbourne Institute of Technology (RMIT) tested 15 volunteers in a virtual simulator that replicates the experience of driving on a monotonous two-lane highway.

The simulator was set up on a platform that could be vibrated on different frequencies, with the volunteers tested twice – once with vibrations at low frequencies (4-7Hz) and once with no vibration.

By looking at the volunteers’ heart rate variability (HRV), researchers were able to gain an objective measure of how drowsy drivers were feeling as the 60-minute test progressed.

The results

Within 15 minutes of starting the vibrating test, volunteers were showing signs of drowsiness. Within 30 minutes, the drowsiness was significant, requiring substantial effort to maintain alertness and cognitive performance. The drowsiness increased progressively over the test, peaking at 60 minutes.

“When you’re tired, it doesn’t take much to start nodding off and we’ve found that the gentle vibrations made by car seats as you drive can lull your brain and body,” Professor Fard explained.

“Our study shows steady vibrations at low frequencies – the kind we experience when driving cars and trucks – progressively induce sleepiness even among people who are well rested and healthy.

“From 15 minutes of getting in the car, drowsiness has already begun to take hold. In half an hour, it’s making a significant impact on your ability to stay concentrated and alert.”

So, what can be done to cut down on the tragedies cause by sleepy drivers?

The RMIT study suggests manufacturing cars that minimise vibrations as the car moves would be a big help to reducing fatigue.

“We want to study a larger cohort, particularly to investigate how age may affect someone’s vulnerability to vibration-induced drowsiness as well as the impact of health problems such as sleep apnoea,” Professor Fard said.

By conducting further research, the team hoped to examine how vibrations could affect various demographics differently.

Moreover, not all vibrations on the road are bad, according to the researchers. The findings suggested vibrations at certain frequencies could actually have an opposite effect and keep people awake and alert.

Do you feel tired when you drive?