woman drinking coffee while drivingDrowsy driving is a major problem, but it’s been significantly harder to nail down than impaired or aggressive driving. The National Highway Traffic Safety Administration estimates that drowsy drivers cause tens of thousands of crashes each year, resulting in property damage, injuries, and deaths. All of these are preventable. According to surveys by the National Sleep Foundation, 60% of Americans admit to having driven while sleepy. What’s more shocking is that 37% admit to having fallen asleep at the wheel during the last year. According to CDC surveys, 1 out of 25 adults admit to having fallen asleep while driving in the last 30 days.

What is Drowsy Driving?

Drowsy drivers get behind the wheel when they have not had enough rest to properly concentrate and drive safely. Safe driving requires you to pay attention and react to new situations quickly. This includes following all traffic signals and watching for other drivers, appropriately giving right of way or getting out of the way if others do something unexpected.

It becomes much more difficult to concentrate on safe driving if you have not had sufficient rest. A recent study from AAA found that drivers are four times as likely to crash if they’ve only gotten 4 to 5 hours of sleep. They’re twelve times as likely to crash if they’ve had less than four hours of sleep.

Other studies say drowsy driving is just as bad as drunk driving. The National Sleep Foundation estimates that being awake for 18 hours straight and driving is much like getting behind the wheel with a blood alcohol concentration of .05. If you’ve been awake for 24 hours, it’s like having a BAC of .10, which is well over the legal limit.

Causes of Drowsy Driving

Lack of Rest

Lack of rest is the most obvious cause of drowsy driving. Certainly everyone has insomnia or a short night of sleep from time to time, but for others it is a chronic problem. New parents, shift workers, and people who work multiple jobs are especially at risk for drowsy driving.


Alcohol can also induce drowsy driving, even if you are no longer impaired. For example, if you do the responsible thing and stay the night at a friend’s house after the party, your BAC may come down to zero by morning. Despite that, it might not be safe for you to drive right away. You may still be too mentally and physically exhausted after your night of partying to safely drive.


Sleepiness as a side effect from medications is another significant cause of drowsy driving. When the label says not to operate heavy machinery, this means it is unsafe for you to drive. If a doctor or dentist warns you about drowsiness after outpatient treatments, you should always heed their warnings.

Untreated Sleep Disorders

Narcolepsy is a neurological disorder that causes significant disruption to sleep. Those who suffer from narcolepsy might also suddenly fall asleep without notice. It’s critical to seek treatment for this disorder if you must drive. Another more common sleep disorder is sleep apnea, which can leave you with chronic exhaustion even if you have gotten 8-10 hours of sleep. Not only does it put you at risk for drowsy driving, it can also impact your heart health. If you are overweight, snore heavily, or ever stop breathing during sleep, you need to seek treatment.

Signs That You Should Stop and Rest

Most people who fall asleep at the wheel don’t realize it’s happening. They tell themselves they can make it to their destination. They blare loud music, guzzle coffee, and even pinch and slap themselves in an effort to stay alert. But the fact is that none of this stuff really works consistently. It’s unsafe to assume these things will keep you alert enough to avoid a crash.

Some of the signs it’s time to pull over and rest include:

  • Repeated yawning
  • Frequent blinking
  • Eye rubbing
  • Difficulty keeping eyes open
  • Trouble keeping head up
  • Wandering or disconnected thoughts
  • Deep daydreaming, such that you don’t remember the last few miles
  • Missing turns or other traffic signals
  • Startling at the sight of other vehicles
  • Drifting onto the shoulder or into the neighboring lane
  • Repeatedly hitting rumble strips

Drowsy Driving Prevention Initiatives in Maryland

The Governors Highway Safety Association recently awarded money to the state of Maryland to develop drowsy driving safety campaigns. We’re proud of be one of just four states to receive one of these grants. The funds will aid in development of educational materials and social media campaigns targeting nurses and others who do shift work in medical settings. This is just the beginning, but it targets one of the groups most at risk for drowsy driving in our state. It’s yet another critical contribution to our overall goal of eliminating deaths on Maryland roads.