Is your car making you sleepy?

A recent Australian study suggests that we may get drowsy while driving because of steady vehicle vibrations at low frequencies.

Robinson’s team found a significant increase in driver drowsiness within 15 to 30 minutes when there were consistent low frequency vehicle vibrations.

They hypothesize that car vibrations at the frequency of 4 – 7 Hz start slowing our brain waves toward 4 – 7 Hz.  When the predominance of our brain waves are this slow, we drift toward sleep.

This may explain why putting your baby on the clothes dryer while it is running,                       or driving them around the neighbourhood, helps them to fall asleep.

To help us stay awake behind the wheel, this research may result in new vehicle designs to absorb or counter low frequency vibration, or perhaps add in vibration at frequencies that keep the brain more alert.

In the interim, if you suspect that your current vehicle is lulling you to sleep with its vibration, try upgrading the tires or suspension, or take off the cruise control when driving for long stretches since varying your speed may impact the frequency of vibration.

We cannot tell when we’re just about to fall asleep (after all, no one plans to fall asleep when they’re behind the wheel), but we do notice when we’re drowsy and that’s an important signal.

Alertness and judgement are impaired.

If you’re drowsy you can fall asleep at any time.

Or have micro-sleeps of 5 – 25 seconds, which is more than enough time to cross the line and have a lethal collision.

Caffeine, chewing gum, and singing aloud will not prevent falling asleep when you’re driving drowsy.

Sleep is the only remedy.


So if you are getting drowsy while on the road :

*  pull over as soon as possible at the nearest safe location,

*  turn your vehicle off, lock the doors and take a short nap.

Even a short 10 minute nap will have a significant impact –  and it could save lives.


Signs that you’re getting drowsy behind the wheel include:

  • tired eyes, eyes closing, or eyes going out of focus
  • hard to keep your head up
  • frequently yawning
  • wandering, disconnected thoughts
  • hard to concentrate
  • feelings of drowsiness
  • bored, irritable or restless
  • slow reaction times
  • don’t remember driving the last few miles
  • drifting between lanes or off the road, or tailgating
  • erratic braking
  • inconsistent speeds
  • no longer checking the mirrors
  • missing traffic signs or exits
  • jerking the car back into your lane

If you experience any of these while driving, pull over at a safe place and get some sleep.

Driver fatigue severely impairs alertness and judgment

and it can affect anyone.

Drive safe. 


For effective, practical stress management skills that enhance health and performance, check out the Stress Management & High Performance Clinic programs at

Kathy Somers, R.Kin, BCB



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