One out of every 24 motorists you pass on the highway are “driving drowsy,” according to a Center for Disease Control and Prevention (CDC) study.

The occurrence is linked to between 5,000 and 6,000 fatal car crashes annually.

“Among nearly 150,000 adults aged at least 18 years or older in 19 states and the District of Columbia, 4.2 percent reported that they had fallen asleep while driving at least once in the previous 30 days,” the CDC said. “Individuals who snored or usually slept six or fewer hours per day were more likely to report this behavior.

The study was conducted through telephone surveys by the Behavioral Risk Factor Surveillance System between 2009 and 2010.

Researchers found that 2,181 men of the 56,321 surveyed reported that they had fallen asleep behind the wheel within the past 30 days. That number was 2,120 for the 90,755 men interviewed.

The report also found that drowsy driving occurs more among younger adults between 18 and 44 than among those over 65.

According to the CDC study, getting behind the wheel with less than eight hours sleep is like driving with a blood alcohol content level (BAC) of 0.05 percent.

“After about 24 hours awake, impairment is equivalent to a BAC of 0.10 percent, higher than the legal limit in all states,” the CDC said in a drowsy driving fact sheet.

According to the National Sleep Foundation, signs that a driver is possibly too sleepy to operate a motor vehicle include “frequent blinking,” “trouble remembering the last few miles driven” and forgetting or completely missing interstate exits.

“Wandering or disconnected thoughts” are also listed as warning signs, along with repeated yawning, tailgating, or “drifting” into other traffic lanes.

The National Institutes of Health (NIH) recommends that teens receive between nine and 10 hours of sleep per night. Adults are encouraged to get between seven and eight hours sleep per day.