Nearly one in 20 Marylanders questioned about their sleep habits by the federal Centers for Disease Control and Prevention told researchers that they had nodded off or fallen asleep while driving at least once during the previous 30 days.
The telephone survey, reported Friday in the CDC's Morbidity and Mortality Weekly Report, found that 4.6 percent of the 3,910 Marylanders who participated in the study admitted dozing at the wheel. The rate was higher than that in eight of the 12 states surveyed.
Drowsy driving is one of the most dangerous consequences of inadequate sleep. The National Highway Traffic Safety Administration says it is a factor in an estimated 1,550 highway fatalities and 40,000 injuries each year in the United States.
"Sleepiness reduces vigilance while driving, slowing reaction time, and leading to deficits in information processing, which can result in crashes," the study said.
Nearly 40 percent of the Marylanders surveyed reported getting less than seven hours of sleep, on average, in a 24-hour period. That compared with 35.3 percent among the 74,500 people surveyed in 12 states.
Seven hours is the amount of shut-eye the National Sleep Foundation suggests healthy adults need. Other studies have found that people who get too little sleep are more at risk for cardiovascular disease, diabetes, depression and obesity, as well as poor general health, frequent mental and physical distress, anxiety and pain.
"Sleep disorders are common health concerns that can be evaluated and treated," the CDC said. "However, many health care professionals may have only limited training in somnology and sleep medicine, impeding their ability to recognize, diagnose and treat sleep disorders or promote sleep health to their patients."
Nearly 49 percent of the Marylanders in the CDC study reported snoring, an indicator of sleep disturbances. And 40.7 percent said they had fallen asleep during the day at least once in the previous 30 days, more than in all but one of the 12 states.
Among all the study participants, falling asleep at the wheel was most common among those 25 to 34 years old — 7.2 percent. It was least common among those 65 and older — 2 percent.
Older people were also the least likely to report getting less than seven hours of sleep on average, at 24.5 percent. The most sleep-deprived group in the study was non-Hispanic blacks, nearly half of whom (48.3 percent) said they got less than seven hours of sleep in a 24-hour period.