Boston Globe - Dangers of Driving While Drowsy

Drowsy-driving tragedies preventable

By Charles A. Czeisler

August 3, 2009

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RECENTLY, the National Transportation Safety Board announced that drowsy driving was the probable cause of the fatal collision of two MBTA Green Line trains in Newton last year. The safety board concluded that MBTA operator Ter’rese Edmonds, who was killed in the crash, did not respond to a red stop signal, likely because she briefly fell asleep at the wheel.The board concluded that she was at high risk for having an undiagnosed sleep disorder known as obstructive sleep apnea. Urine drug testing also revealed her prior use of a sedating antihistamine commonly used in over-the-counter treatments for insomnia, allergies, and the common cold, although the chemical was no longer detectable in her blood at the time of the crash.

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Drowsy driving is one of the most common causes of crashes in all modes of transportation. The board has also found that fatigue is the most common cause of fatal-to-the-driver truck crashes - equal to drug- and alcohol-related crashes combined. Auto drivers are no exception. Every day in the United States, 250,000 motorists fall asleep at the wheel, causing 8,000 deaths and 60,000 debilitating injuries annually. Fortunately, such tragic drowsy-driving crashes are preventable.

Earlier this year, the Massachusetts Drowsy Driving Commission, chaired by state Senator Richard T. Moore of Uxbridge, made a series of recommendations to reduce drowsy-driving crashes. Education about the risks of drowsy driving is a critical first step, which is why the safety board faulted the MBTA for having an inadequate program for educating train operators about the risks of fatigue. The diagnosis and treatment of sleep disorders is a second critical step, which is why the board faulted the MBTA for having an inadequate program to identify and treat sleep disorders among train operators.

Sleep disorders and sleep deprivation - which affect 50 million to 70 million Americans - increase the risk of attentional failures and distraction, lengthen reaction time, degrade cognitive performance, impair immune responses, increase mood swings, and interfere with memory consolidation and learning. Yet the Institute of Medicine recently estimated that 90 percent of Americans with the sleep disorder known as obstructive sleep apnea are undiagnosed and untreated.

Sleep disorders medicine is given scant attention in most medical schools and academic medical centers, which chronically sleep-deprive physicians-in-training by scheduling them to work 30-hour shifts twice each week, to the detriment of both the trainees and their patients. Consequently, even when a patient seeks help from a doctor for the symptoms of obstructive sleep apnea, it can often take several years to be correctly diagnosed. Then, only half of those diagnosed comply with treatment, yielding a 5 percent success rate.

We can and should do better because obstructive sleep apnea is a serious disease. It robs individuals of the restorative value of sleep, since they have difficulty breathing during sleep. Many awaken more than 100 times a night in order to breathe. Choking off the air supply during sleep activates the sympathetic nervous system and increases blood pressure. In fact, untreated obstructive sleep apnea is the leading known cause of hypertension, or high blood pressure, likely accounting for an estimated one-third of cases. Obstructive sleep apnea alters metabolism and may increase risk of obesity, diabetes, atrial fibrillation, ventricular arrhythmias, and sudden cardiac death at night.

Obstructive sleep apnea increases the risk of motor vehicle crashes by 500 to 700 percent and raises medical costs. Schneider Trucking recently reported that introduction of a screening and treatment program for obstructive sleep apnea among drivers in its trucking fleet reduced fatigue-related truck crashes by 30 percent, cut medical costs in treated drivers by 58 percent, and increased its driver retention rate.

The effects of sleep disorders and sleep deprivation on driver performance are comparable to those of elevated blood alcohol concentrations, and should be taken just as seriously. Identification and treatment of sleep disorders such as obstructive sleep apnea can reduce the risk of crashes and improve public safety. It is time to implement the recommendations of both the safety board and the Massachusetts Drowsy Driving Commission to reduce the risks of one of the leading preventable causes of transportation crashes: fatigue.

Charles A. Czeisler, a professor and director of sleep medicine divisions at Harvard Medical School and Brigham and Women’s Hospital, was a member of the Massachusetts Drowsy Driving Commission.

© Copyright 2009 Globe Newspaper Company.