Drowsy Driving

Illustration by Melinda BeckIllustration by Melinda Beck
By Corydon Ireland

If you haven’t slept in 24 hours, you’re just as impaired as if you were legally drunk.

American drivers, medical researchers at Harvard have a message for you: Wake up.

Drowsy driving, these researchers say, is an understudied, underappreciated, and underfunded public health and safety concern. Consider a few facts about the act of operating a motor vehicle while sleep-deprived: Every week, 2 million Americans nod off at the wheel; drowsy drivers get into 1.9 million crashes a year; and 20 percent of all serious motor vehicle accidents—one out of every five—involve sleepy drivers. The annual death toll is 7,500, and serious injuries number 50,000.

After all, what is a car, truck, or bus operated by a driver who falls asleep? “It’s a missile,” said Charles A. Czeisler, the Baldino Professor of Sleep Medicine at Harvard Medical School. He helped organize an Exploratory Seminar earlier this year at the Radcliffe Institute. The meeting—from May 9 to 12—addressed two interrelated challenges: new directions for the mathematical modeling that researchers use to predict sleep and wakefulness and new ways to translate sleep research into regulatory standards for wakefulness in operational environments. “We always want our work to be applicable to the real world,” said seminar co-organizer Elizabeth B. Klerman, a researcher in sleep and sleep modeling and an associate professor of medicine at Harvard Medical School.

To start on these challenges, Czeisler and Klerman were joined at Radcliffe by other researchers and by experts from outside the realm of medical science: mathematicians, economists, lawyers, transportation executives, health policy analysts—and one expert each from where this rubber really meets the road: politics, regulation, and law enforcement. They included the Massachusetts state senator Richard T. Moore; Rachel Kaprielian, registrar of the Massachusetts Registry of Motor Vehicles; and Marian J. McGovern, superintendent of the Massachusetts State Police. Also on hand were two sleep and safety experts from Australia, where drowsy-driving policies are solidly in place. The traffic police there make 4 million random stops a year looking for sleepy or drunk drivers—who, physiologically, share many impairments.

Up to 20 times a year, the Radcliffe Institute provides funding and a venue for disparate experts to define new questions, test hypotheses, and advance knowledge. The program invites seminar proposals from Harvard faculty members or former Radcliffe fellows. Since 2002, the seminars have fanned like bright comets across a firmament of issues. For 2010–2011, they include seminars on condensed-matter astrophysics, sound art, and the narrative confluences of fiction and evolutionary biology. No matter what the subject, the core themes at Exploratory Seminars are always the same: take risks, ask new questions, and push boundaries.

“I don’t usually talk to somebody at a law school about our work,” said Klerman, who directs the Analytic and Modeling Unit within the Division of Sleep Medicine at Brigham and Women’s Hospital. “You get out of your silo.” Czeisler, who is chief of the same division, agreed that the Radcliffe setting creates some novel dialogues. “That was one of the highlights of the Radcliffe seminar,” he said, “to bring people together and share perspectives we don’t ordinarily get."

Exploring ways to implement policy based on research and theory “is good for both academics and policymakers,” said Moore. “It allows sharing and collaboration.” In 2009, he coauthored “Asleep at the Wheel,” a special commission report on drowsy driving. (Kaprielian is another coauthor.)

On the medical side, the seminar has already spurred several grant applications related to drowsy driving, says Klerman, along with collaborations with Harvard Kennedy School and the Harvard School of Public Health. Czeisler is writing a journal article on the legal implications of extended-duration work shifts with coauthors I. Glenn Cohen of Harvard Law School and Christopher P. Landrigan of Harvard Medical School. And with Australian collaborators, he has begun testing instruments that measure degrees of wakefulness. The team is using infrared reflective oculography to record the velocity of eyelid movement, a telltale sign. During a blink, a sleepy person’s eyelids close at the same rate as those of a rested counterpart, but they reopen much more slowly.

Every week, 2 million Americans nod off at the wheel; 20 percent of serious motor vehicle accidents—one out of every five — involve sleepy drivers.


A related study has already appeared in print, in August. Harvard researchers Chungbai Zhang and Stefanos N. Kales investigated “psychomotor vigilance testing” (PVT) to assess reaction times among commercial drivers and emergency first responders. PVT may help screen drivers who are at risk of daytime sleepiness because of obstructive sleep apnea. Such drivers experience, in medical parlance, “microsleep episodes.”

Policymakers in some realms have already confronted the potentially fatal consequences of mixing sleeplessness with critical work. Regulations or standards are in place for astronauts, truckers, medical residents, and pilots (though not for airline maintenance crews). Meanwhile, more than half of all drivers admit they have occasionally nodded off at the wheel, said Czeisler. Most such drivers also admit they are unlikely to take any action other than to keep going. That attitude stems from a lack of public education, he said. About $300 million a year goes to educating the public about drunk driving, but less than 1 percent of that amount is used to wake people up to the hazards of drowsy driving. If you have not slept in 24 hours, said Czeisler, “you’re just as impaired as if you were legally drunk."

Those most at risk for drowsy driving are males aged 16 to 29, drivers with undiagnosed sleep disorders, commercial drivers, and people working long shifts or night shifts. “Unfortunately,” Klerman said, “people don’t know how tired they are."

Another problem is that driving itself is a “routine, highly overlearned task,” said Czeisler. You can be practically asleep, but “automatic behavior syndrome” takes over and makes it appear, for a time, as if you were driving competently. He cited the case of a woman in the netherworld between wakefulness and sleep who for 30 minutes drifted into other lanes of traffic and nearly ran several trucks off the road along I-25 in Denver before she was stopped by the police. When you are drowsy, said Czeisler, “your judgment is impaired.”

Meaningful enforcement of laws against drowsy driving will need the equivalent of a Breathalyzer, said Moore; although, he added, it’s getting better with the advent of devices that warn drivers when a vehicle crosses the center line. Klerman agreed that for now, scientists have no Breathalyzer equivalent, or even a biomarker that signifies sleepiness. In the meantime, she said, more education is the key.

Adults need eight hours of sleep a night but often get less, Klerman said. (It should take 10 or 15 minutes to fall asleep at night, she said—and if you fall asleep right away, especially during the daytime, you’re not getting enough. Ditto if you find yourself sleeping 10 to 12 hours a night on weekends.) Getting enough sleep does more than allay drowsy driving: It’s tied to good hormone function, a healthy immune system, and learning acuity. It also reduces the risk of obesity. “People need to recognize the importance of sleep,” said Klerman. “It’s not a waste of time."

In the meantime, the most dramatic and public consequences of drowsiness take place on the road. Klerman recalled a woman who told her, “I fall asleep at red lights. Is that OK?” Another woman thought she had found the answer to staying awake on the road: clamping her ponytail in the sunroof so that every nod would jerk her awake.

But the real answer involves what nature intended, experts say: Get enough sleep. And when you get behind the wheel of a car, be awake.

Search Year: 
2012