Sleeping behind the wheel kills hundreds of thousands of people each year. According to Transport Canada, an average of twenty per cent of all fatal collisions are due to driver fatigue. The stakes are even bigger with truckers who drive long hauls. New research and practical solutions testings from RMIT University in Australia may have a solution.
The researchers found that the vibrations from your vehicle — the steady, rhythmic motion — may actually be creating a resonance with our brain and body, similating theta waves, in effect, hypnotizing us into “sleep mode.”
This doesn’t occur so much during acceleration, or on the S-curves and mountain roads, but it’s a major factor on highway drives. The researchers found that as little as fifteen minutes of open road — coached the low-frequency vibrations — is enough to bring on the yawns, and the danger.
With the danger identified, ergonomic and mechanical tuning solutions become possible.
Danger Dr Robinson!
The researchers found, through simulators (see video below), that the vibrations, transferred through the seats, contributed to the feeling of fatigue and drowsiness. As Professor Stephen Robinson, head of psychology at RMIT explains in the video: “We believe that what’s happening is that the sensory input that’s coming from the vibrations is starting to synchronize the brain waves and put the brain into an early stage of sleep.”
The frequency of seat vibrations is close to that of theta waves, associated with the early sleep state.
Video: How VIbrations in Cars:
In related precursor research to the RMIT project, Japanese researchers had found that the rhythm and vibration of a train lulled passengers to sleep. This led to a testable frequency range of 4 to 7 Hertz for the RMIT simulator.
Testing the hypothesis
To test their theory, the engineering team at RMIT rigged up a simulator, including a car seat on a vibrating platform. VR technology — a steering wheel and controls, with a screen simulation — is used to replicate the sense of the open road.
The seat vibrated at the low frequencies associated with highway thrum, a frequency range of 4 to 7 Hertz. The same test was conducted without vibrations.
All of the volunteers in the experiment were young, averaging 23 years of age, and represented both sexes. The volunteers were fully rested and engaged in hour-long tests each day. The simulator experience was deliberately reflective of straight and non-challenging highways. Between boredom and vibrations, the young volunteers were soon demonstrating fatigue.
The researchers used eye-tracking technology to track the drift of the eyes off the road and the “droop” of the eyelids. “The car typically does an S shape all the way up the road as we get very tired,” said Dr Robinson.
They also found that just fifteen minutes was enough to induce enough drowsiness in an alert 23-year-old to increase the risk of a crash.
In the simulator, the subjects only had to stay on the road and not crash. With the vibrations, they started to have trouble staying awake — let alone alert.
Researchers also measured heart rate responses. On the days when subjects were tested with vibrations, eye droop and heart rate demonstrated less alertness, as compared to days when there was no vibration.
With the problem identified, solutions become apparent. Various ideas for solutions include
- shock absorbing seats
- vibration-cancelling technology (modulating frequencies of seat vibrations to counter the effect)
- more padding on seats
- modulating the actual vibrations of the vehicle itself.
Until technological advances are made in automotive engineering, drivers can try a few tips:
- take frequent breaks
- vary the speeds on the highway
- avoid cruise control, which is too “soothing”
- use energetic music
- bring along the kids — screaming and fighting kids are sure to keep you alert.
NOTE: No specific advice is offered to drivers in this feature. This research and any suggestions are simply findings of current research.