CBS News Correspondent Bob McNamara reports they have special reason to be concerned when their children get tired and get behind the wheel of a car.
It's their worst nightmare when they hear the news that a child fell asleep and was killed in a car crash.
"Its like part of you died. And you can never get that back. You can't fill that hole," says Darla Drentlaw.
Drentlaw's heartache is her daughter, Katie a Minnesota high school star athlete who was almost home from an Iowa track meet when she fell asleep at the wheel and was killed.
"I just miss her... (quietly) a lot," says Drentlaw.
This year, America's drowsy drivers will figure in more than 1,500 traffic deaths. So many of the victims are teen-agers and young adults that safety and sleep experts call it an epidemic.
"Fall-asleep car crashes probably kill more Americans under the age of 25 than alcohol related accidents," says Dr. Mark Mahowald, a sleep expert.
Recently, two Minnesota safety and health agencies did a driving and sleep study, using a couple of college students.
After a week of normal sleep, both young drivers did well, safely reacting to simulated hazards.
But in 24 hours, after being awake all night -- like students cramming for finals -- the two students were different drivers, performing poorly. One of them fell asleep at the wheel, stopped steering and failed to stop, later saying she didn't even remember she was driving half of the time.
"They were as impaired behind the wheel as if they had a blood alcohol level point-one-percent, which is legally intoxicated," says Mahowald.
"You wish it was a dream. You wish it was just not true (lots of tears) its the worst thing ever," says Darla Drentlaw.
But, out there, almost anywhere tonight, it could happen to some one else.