LIVINGSTON - Experts say sleep deprivation can have a profound effect on drivers.

The accident that injured comedian Tracy Morgan and killed one of his friends involved a driver that police say had been awake for more than a day.

"If you're sleep-deprived or if you're awake for 20 hours, your reaction time is about the same as being intoxicated to the legal limit of .08," says sleep physician Dr. Kristen Fless. "It does impair your reaction time enough to qualify as being impaired."

Experts at the Center for Sleep Disorders at St. Barnabas Medical Center in Livingston say drowsiness cannot be overcome with caffeine or energy drinks.

Drowsy drivers will often lapse into what are known as "micro-sleeps" that can last up to 30 seconds, doctors say.

In a statement, Wal-Mart says, "It is our belief that Mr. Roper was operating within the federal hours of service regulations. The details are the subject of the ongoing investigation and we are cooperating fully with the appropriate law enforcement agencies. Federal law requires drivers to work no more than 14 hours for any shift and 11 hours of driving."    

The National Highway Traffic Safety Administration says drowsy driving is linked to 100,000 crashes a year, resulting in 40,000 injuries and more than 1,500 deaths.