More than one in four motorists (28 percent) reported being so tired they had a hard time keeping their eyes open while driving in the past month, according to new research by the AAA Foundation for Traffic Safety.

Motorists ages 19-24 were the most likely to report driving dangerously drowsy (33 percent), while drivers 75 and older and drivers ages 16-18 were the least likely to report having done so in the previous month (22 percent each).

“Drowsy driving remains a significant threat to the motoring public, with many drivers underestimating the problem of driving while extremely tired, and overestimating their ability to deal with it,” said Peter Kissinger, president and CEO of the AAA Foundation for Traffic Safety. “Driving while fatigued is dangerous because it slows reaction time, impairs vision and causes lapses in judgment, similar to driving drunk. We know that people can’t reliably predict when they are going to fall asleep, and a very fatigued driver may fall asleep for several seconds without even realizing it.”

The study found that 95 percent of drivers believe it is somewhat or completely unacceptable to drive when they are so tired it is difficult to keep their eyes open. More than eight in 10 (83 percent) believe that drowsy drivers pose a somewhat or very serious threat to their personal safety.

“Many of us are so worn out from our work and family obligations, yet we downplay our fatigue and stay behind the wheel even when we should stop for a rest,” said Jake Nelson, AAA Director of Traffic Safety Advocacy and Research. “We should consider the dangers whenever we attempt to push our driving to the limits. We can protect ourselves and everyone else on the road by recognizing the simple signs of fatigue.”

An estimated 17 percent of fatal crashes, 13 percent of crashes resulting in hospitalization, and 7 percent of all crashes requiring a tow involve a drowsy driver, according to a 2010 study by the AAA Foundation for Traffic Safety.

Some warnings signs that may signify drowsiness while driving are:

• The inability to recall the last few miles traveled

• Having disconnected or wandering thoughts

• Having difficulty focusing or keeping your eyes open

• Feeling as though your head is very heavy

• Drifting out of your driving lane, perhaps driving on the rumble strips

• Yawning repeatedly

• Accidentally tailgating other vehicles

• Missing traffic signs.

AAA urges all motorists to stop driving and find a safe place to pull over if experiencing any of the drowsy driving symptoms. To remain alert and be safer behind the wheel, AAA has these suggestions you can pass along to your fleet drivers:

• Get plenty of sleep (at least seven hours), especially the night before a long drive

• Drive at times when you are normally awake

• Schedule a break every two hours or every 100 miles

• Avoid heavy foods

• Travel with an alert passenger and take turns driving whenever possible

• Avoid medications that cause drowsiness or other impairment

• Consult with a sleep specialist or other medical professional if you have trouble getting enough rest or are chronically fatigued.

The AAA Foundation for Traffic Safety collected the data as part of the 2013 Traffic Safety Culture Index. A total of 2,325 licensed drivers were surveyed using a web-enabled probability-based panel representative of the U.S. population.