The study, authored by Diana Dolan, of Sleep Medicine Associates of Texas, focused on 263 students at the University of North Texas, who completed a survey that included demographics and sleepiness measures. Students were asked to respond "yes" or "no" to the items: "Have you ever fallen asleep at the wheel?" and "Have you ever gotten into a wreck because you were sleepy?"

According to the results, 17 percent of students reported falling asleep behind the wheel, while 2.2 percent actually had accidents related to falling asleep. Importantly, 67 percent of those who reported accidents had significant levels of daytime sleepiness. Also, 59 percent of those who reported falling asleep at the wheel were found to have significant sleepiness. Students having difficulty driving due to sleepiness reported fewer hours of sleep than those without difficulty.

"The results of the study identify a surprisingly high prevalence of having fallen asleep while driving among college students, and specifically highlight the increased risk of driving among those with significant sleepiness," said Dolan.

Drowsy driving, the dangerous combination of sleepiness and driving, or driving while fatigued, while operating a motor vehicle, is becoming a growing problem in the United States.

Drowsy driving results in a slower reaction time, decreased awareness, impaired judgment and an increased risk of getting involved in an accident, resulting in unnecessary deaths or injuries to innocent people. Nearly nine out of every ten police officers responding to an AAA Foundation for Traffic Safety Internet survey reported they had stopped a driver who they believed was drunk, but turned out to be drowsy. The survey was coordinated with the National Highway Traffic Safety Administration (NHTSA),

There are two main causes of drowsy driving:

Sleep restriction: Persons getting less than the recommended seven-to-eight hours of sleep each night are more likely to feel tired the following day, which can ultimately affect their cognizance behind the wheel. Not getting enough sleep on a consistent basis can create "sleep debt" and lead to chronic sleepiness over time. While some factors, including working at a job that requires long hours and familial responsibilities, are beyond a person's control, other reasons for sleep restriction represent a lifestyle choice. This includes sleeping less to have more time to work, study, socialize or participate in other activities.

Sleep fragmentation: Sleep fragmentation causes an inadequate amount of sleep and can negatively affect a person's functioning during the daytime. Sleep fragmentation can have internal and external causes. The primary internal cause is sickness, including untreated sleep disorders. External factors that can prevent a person's ability to have a full, refreshing night of sleep include noise, children, bright lights and a restless bed partner.

Drowsy driving is the direct cause of approximately 100,000 police-reported crashes annually, resulting in an estimated 1,550 deaths, 71,000 injuries and $12.5 billion in monetary losses, according to NHTSA.

The American Academy of Sleep Medicine (AASM) offers the following ways to avoid becoming drowsy while driving:

• Get enough sleep

AASM recommends that adults get seven-to-eight hours of sleep each night in order to maintain good health and optimum performance.

• Take breaks while driving

If you become drowsy while driving, pull off to a rest area and take a short nap, preferably 15-20 minutes in length.

• Consume caffeine

Caffeine improves alertness in people who are fatigued.

• Do not drink alcohol

Alcohol can further impair a person's ability to stay awake and make good decisions. Taking the wheel after having just one glass of alcohol can affect your level of fatigue while driving.

• Do not drive late at night

Avoid driving after midnight, which is a natural period of sleepiness.

Those who suspect that they might be suffering from a sleep disorder are encouraged to consult with their primary care physician or a sleep specialist.

Note: If no author is given, the source is cited instead.

• Sleep Disorder Research
• Insomnia Research
• Staying Healthy

• Sleep Disorders
• Insomnia
• Obstructive Sleep Apnea

• Narcolepsy (sleep disorder)
• Narcolepsy
• Circadian rhythm sleep disorder
• Delayed sleep phase syndrome
• Fatigue (physical)
• Sleep deprivation