November 17, 2018
Businessman driving a car

DWD: Driving While Drowsy

by Berkeley Wellness  

We’ve written (and warned) about drunk driving and, more re­­cently, about the dangers of texting while driving. But what about driving while drowsy? How risky is that?

Very, according to a report from the AAA Foundation for Traffic Safety. Using data collected on 7,234 drivers involved in crashes in the mid-2000s, in­­vestigators compared the sleep times of drivers who had crashed due to some un­­safe action (or inaction) to those who crashed for other reasons (such as mechanical failure or environmental conditions).

Compared to drivers who slept seven hours in the previous 24 hours, those who slept five to six hours had nearly double the crash rate; those who slept four to five hours had more than quadruple the risk (equal to driving drunk); and those who slept less than four hours were nearly 12 times more likely to crash (equal to driving very drunk).

The researchers also looked at the data in terms of drivers’ customary sleep times. Drivers who slept one to two hours less than usual had a 30 percent in­­creased risk of crashing the next day; missing two to three hours of usual sleep nearly tripled the risk. When they missed four or more hours, the risk of a next-day crash in­­creased 10-fold. Among some limitations, the study relied on self-reported sleep time, did not explain why drivers got less-than-optimal sleep, and did not look at the effects of chronic sleep deprivation.

The foundation previously estimated that drowsiness behind the wheel ac­­counts for as many as 7 percent of all crashes and 16 to 21 percent of all fatal crashes. People who are sleep-deprived have slower reaction times and are less accurate in their responses and less attentive to stimuli overall. They may have trouble keeping their eyes open, may find themselves drifting from lane to lane, and may not remember the last few miles driven. Worse yet, many people fall asleep at the wheel with no warning signs.

Stay awake while driving

Everyone differs in terms of how much sleep they need, but the National Sleep Foundation recommends that most healthy adults get seven to nine hours a night. Many people don't achieve that. An estimated one-quarter to one-third of all adults—and half of those over 65—regularly suffer from insomnia, and nearly everybody has it at some time. Many people also don’t get enough sleep because of overextended schedules, children waking at night, medical problems, or other reasons.

This report underscores the need to address any sleep problems you have—such as getting evaluated and treated for sleep apnea if needed, learning ways to combat insomnia (one of the best treatments is cognitive behavioral therapy), and prioritizing sleep over other activities when possible. You should also, of course, not drive after taking medications that cause drowsiness.

If you find yourself getting drowsy while driving, have a passenger take over, or pull off to a safe area to rest. On long trips, consider taking regular rest breaks, say, every two hours or 100 miles.