Sleep Apnea and Drowsy Driving

man driving a car wearing wrist watch

Serious Car Crashes and Excessive Daytime Sleepiness

Sleep apnea and drowsy driving double the risk of traffic accidents and significantly increase the risk of personal injury during a car crash.

Drowsy driving occurs when tired drivers fall asleep at the wheel. No one knows exactly how many car crashes and fatal accidents arise from drowsy driving, as sleepiness is difficult to quantify. Use of alcohol and drugs can be proven after an accident; drowsy driving can be inferred, but only reports from drivers or passengers can really prove whether or not sleepiness was a factor in a car crash.

The National Sleep Foundation, working with the National Highway Traffic Safety Administration, estimates at least 100,000 car crashes a year are caused by drowsy driving in the U.S., and that sleepy driving accounts for at least 1,550 deaths a year.

Causes of Drowsy Driving

A number of factors contribute to drowsy driving. Sleep deprivation is epidemic in modern life. Indeed, some people take pride in how little sleep they “need.” Loss of sleep impairs reaction time, performance, and judgment, all of which are needed to drive safely.

Night shift workers are especially vulnerable to sleep deprivation, so much so that peak hours for drowsy driving occur between midnight and six in the morning. Sleep disorders such as sleep apnea, insomnia, and narcolepsy all increase the risk of drowsy driving and serious accidents.

Sleep apnea occurs when a person stops breathing for ten or more seconds while asleep. The pause in breathing, or apnea, arouses the brain from sleep in order to resume breathing. Apneas may occur multiple times over the course of the night, leading to excessive sleepiness during the day.

Sleep Apnea and Drowsy Driving

A Canadian study published in the February 2008 issue of Thorax sheds some light on the relationship between sleep apnea and drowsy driving. The study examined data from a source with a vested interest in monitoring car accidents: insurance companies.

The Vancouver Coastal Health Research Institute ran the study in cooperation with the University of Beitish Columbia. The Insurance Corporation of British Columbia provided the data, which included 1,600 files of people with and without sleep apnea symptoms.

The results were alarming. People with sleep apnea are twice as likely to be in a car accident when compared with the general population. The car crash is also likely to be more serious; the rate of personal injury due to car crashes amongst people with sleep apnea is three to five times normal.

In the general population, men are more at risk of being involved in a car accident than women. When sleep apnea is a factor, the risk of a car crash is the same for both men and women.

Sleep apnea symptoms did not have to be severe to increase the risk of a serious car crash. According to Dr. Najib Ayas, associate professor of medicine at the University of British Columbia, even “fairly mild sleep apnea” increased the risk of “serious crashes.”

Sleep apnea is a common sleep disorder. The majority of people with sleep apnea are unaware that they have a problem, and don’t receive any treatment for the condition. A sleep study is necessary for sleep apnea diagnosis, after which a number of treatment options are available for the disorder, including surgery, dental mouthpieces, and CPAP machines.

Disclaimer: The information contained within this article is for informational purposes only, and is not intended to be a substitute in any way for care and treatment by a qualified health professional.


Drowsy Driving. (n.d.). What is Drowsy Driving?

National Safety Council. Drowsy Driving.

Science Daily. Sleep Apnea Doubles Car Crash Risk, Study Finds.