A recent study from the AAA Foundation for Traffic Safety found that drowsiness may be a factor in at least 10 percent of traffic crashes.
Most previous studies of drowsy driving have been based on crash characteristics that are commonly associated with drowsiness, such as lane departure or failure to brake before impact. Some studies have been based on results from driving simulators or from drivers’ self-reports of drowsy driving – methodologies that have substantial limitations. The AAA study, however, provides a reliable estimate of the number of crashes involving drowsy drivers.
The AAA study recruited 3,593 drivers between 2010 and 2013 to participate in the study, equipping their vehicles with dashboard cameras and data collection equipment. Data scientists calculated PERCLOS – the percentage of time a driver’s eyes were closed in the final three minutes preceding a crash. PERCLOS data showed that drivers were drowsy in 9.5 percent of all crashes. More than half of all drowsy-driving crashes occurred in darkness.
There were some limitations in this study. Researchers couldn’t always see a driver’s eyes for a full three minutes preceding a crash, especially if drivers were wearing sunglasses. When researchers looked at only the final minute preceding a crash, 10.6 percent involved drowsy drivers.
What the Results Show
Official statistics from the National Highway Transportation Safety Administration cite driver drowsiness as a factor in only 1.4 percent of all police-reported crashes in the United States and in only 2.4 percent of fatal crashes annually, between 2011 and 2015. Based on the AAA study, it seems the NHTSA has underestimated the prevalence of drowsy driving.
The AAA researchers acknowledged that even their own study may underestimate the number of crashes caused by drowsy driving, because study participants knew they were being recorded and may have been less likely to engage in risky driving behaviors.
How Much Sleep Drivers Really Need
In 2015, the National Sleep Foundation assembled a panel of experts to discuss how much sleep people need in order to safely drive. The panel concluded that a person who has less than two hours of sleep in the prior 24 hours is unfit to drive.
A lack of adequate sleep over time can create “sleep debt” – that means with each successive day of too little sleep, the body suffers more and more ill effects, such as poor judgment, uncontrollable drowsiness, moodiness, and poor motor skills.
How to Avoid Drowsy Driving
The National Sleep Foundation urges drivers to be aware of the telltale signs of drowsiness, such as:
- Drifting out of the travel lane or hitting a rumble strip on the road shoulder
- Daydreaming or “spacing out”
- Yawning repeatedly
- Missing exit signs/running stop signs
- Having difficulty focusing
When traveling long distances, it’s best to stop every two hours and, ideally, travel with another person who can share driving time. If you’re ever driving and feel you’re too drowsy to drive safely, find a safe place to pull over, and take a 20-minute nap. Allow about 15 minutes to shake the post-nap grogginess before continuing your journey.
If you believe your traffic accident and injuries were caused by a drowsy driver, contact one of our attorneys for a free consultation.