Short Sleepers and Drowsy Driving

Monday, May 26, 2014

Drowsy DriverDrowsy driving is one of the leading causes of vehicle accidents. To address this problem, researchers have conducted many studies to discover the general sleeping and/or behavioural patterns that cause drowsy driving. Their findings will surprise few. 

According to a University of Pennsylvania Perelman School of Medicine study, those who sleep less than six hours a night are the most likely to report feeling drowsy behind the wheel, even if they drive just after waking up. In fact, these short sleepers are twice as likely to feel drowsy while driving as people who sleep for seven hours. Very short sleepers, defined as those who sleep around five hours, are four times more likely to drive drowsy than those who sleep seven hours. They feel like they get enough sleep, they feel rested when getting into the car, but they start feeling drowsy once they have driven a short way.

This 2013 study was seen as a step forward, because up till then researchers had only tested sleep-deprived drivers in laboratories. The real-world behaviour of the population had not been studied. The Perelman School researchers obtained their data from a large national survey of health-related behaviour in the American population conducted by the Center for Disease Control and Prevention. 

The unique contribution of this research can be explained with reference to another study. A 2004 study found that short sleepers reported daytime alertness and low levels of daytime fatigue. The weakness of this study was that its participants knew they were participating in a study on sleep and the effects of sleep. Since the Perelman School data was derived from a huge survey of numerous different types of behaviour, the participants would not have been able to adjust their answers to reflect what they thought was being studied, because they did not know what was being studied.

There are a small number of people who genuinely need very little sleep. Then there is a much larger group who think they do well on very little sleep. The Perelman School study basically shows that this second group is self-deluded. An interesting future direction for this research is to find people in the first group and subject them to controlled driving tests to verify that their apparently comfortable short sleep does not degrade their driving ability.