A small but scary number of Minnesota drivers are asleep at the wheel.

A new analysis of drivers finds that 3.1 percent of the state's drivers admitted to have fallen asleep while driving in the past 30 days.

That's better than the national average. Nationally, 4.2 percent of the 147,000 drivers surveyed in 19 states and the District of Columbia said they had taken a snooze behind the wheel at least once in the past month.

The analysis was reported this week by the Centers for Disease Control and Prevention, which reviewed data from the National Highway Traffic Safety Administration (NHTSA) in 2009-2010.

The traffic safety agency found that 2.5 percent of fatal crashes and 2 percent of crashes with nonfatal injuries involve drowsy drivers. Other studies estimate that the numbers are much higher, and one study estimated that 15 to 30 percent of fatal crashes involved sleepy drivers.

In its estimates, the NHTSA said 100,000 police-reported crashes are the direct result of driver fatigue. Those crashes led to 1,550 deaths, 71,000 injuries and $12.5 billion in monetary losses.

Sleep-deprived motorists are more likely to be involved in a wreck at night or midafternoon, the CDC report said. Often crashes involve only a single driver going off the road, but they also make up a disproportionate number of rear-end and head-on collisions, the CDC said.

Drivers often are unaware they are sleepy. Signs include frequent yawning or blinking, difficulty in remembering the past few exits or miles driven, missing turns, drifting from lane to lane or hitting a rumble strip.

Those who are aware might try to combat the fatigue by opening a window, cranking the air conditioner or turning up the radio. Those tactics are generally ineffective, the CDC said.

Tim Harlow • 612-673-7768 Twitter: @timstrib