Vibrations contributing to driver drowsiness - study

We've all felt it happening. You're driving along when, all of a sudden, your eyes get heavy and sleepiness starts to kick in. Along with lack of sleep, it turns out vibrations of a certain frequency could be the cause. Speaking on the CarAdvice podcast, RMIT Professor Stephen Robertson said a "narrow range of vibrations that come through the driver's seat can cause drowsiness within 15 to 30 minutes, which is incredibly quick".