A new study suggests that drivers consistently underestimate how tired they are and how much fatigue affects their driving. The findings are scary because crashes caused by tired drivers tend to be severe — nod off behind the wheel, and you won’t be alert to brake or swerve to avoid anything.Researchers compared objective, subjective drowsiness Sponsored by AAA, researchers at the University of Iowa asked 90 drivers to drive 150 miles on a simulated interstate highway at night after a day without caffeine or a nap. Fifty were male, 40 were female, and they averaged 31.4 years old.
Researchers asked the drivers to rate their fatigue on a 9-point scale. They then compared their subjective opinions to an objective measure — the percentage of time their eyelids spent closed. Drivers could stop to take breaks. They could walk around, drink coffee, eat food, or use “a private room with a comfortable chair” to nap. But researchers also told them they earned a dollar for every minute under three hours they drove. Researchers didn’t pay them if they crashed or went off the road. Check out: The eye-opening results scientists found when they studied bug splats on carsDrivers declined to rest The result? Participants significantly underestimated their drowsiness. “When drivers reported low perceived levels of drowsiness, the objective measure suggested tha …