Car vibrations are the culprit that makes drivers sleepy finds study

By Dr. Ananya Mandal, MDJul 9 2018

Long drives and long car journeys can make a person sleepy. While driving this is one of the commonest reasons for accidents with one in five accidents occurring due to sleepiness or fatigue behind the wheels.

Lead author, PhD researcher Neng Zhang, in the virtual simulator.

A team of researchers have found that the vibrations emitted by the car as it runs may be the reason for the drowsiness. They noted that only around 15 minutes of these vibrations are enough to cause a person to feel sleep in a car. The study appeared in the latest issue of the journal Ergonomics.

Researchers at the RMIT University in Australia have warned car drivers along with road safety experts and car manufacturers that this is a vital element to be considered while making and driving cars. Stephen Robinson, one of the study authors said that when a person is tired, it takes little to have them dozing off.

The study, he explained, has found that the gentle vibrations of the car seats are capable of lulling the brains and bodies of these overtired individuals and make them sleepy. He said that these vibrations are “steady” and “low frequency” that are experienced while driving trucks and cars. He said that individuals who are well rested and healthy can also feel progressively sleepy when exposed to these vibrations.

For this study the team experimentally placed 15 volunteers on a virtual simulator that was capable of vibrating at different frequencies. Then the participants were tested once with no vibrations and then again with low-frequency 4-7 Hz vibrations. Over a one hour session the heart rate variations (HRV) of the participants were measured. These variations are indicators of sleepiness. As the brain tires the heart rate tends to change.

Results revealed that within 15 minutes drowsiness was experienced by the participants and by 30 minutes most of the participants started feeling “significantly” sleepy. The sleepiness progressed till the end of the test.

The team of researchers explained that the brain usually gets synchronized with the vibrations and enters into early stages of sleep. This leads to sleepiness. They explain that this study needs to be performed in a larger group of individuals to be of significance and to be applicable in day-to-day scenarios. However, the results still are noteworthy and should be considered for further exploration, they add.

The team says that they plan to try different frequencies in larger groups of participants to see if their hypothesis held true. Robinsons says that some vibrations may keep people awake instead of putting them to sleep.