The common practice of requiring physicians-in-training to work many double, and even triple, shifts results in performance reductions equivalent to the effects of drinking several ounces of alcohol, according to a new study led by a University of Michigan sleep researcher published in the Journal of the American Medical Association.

Depending on the type of medical or surgical care they decide to specialize in, young doctors can spend anywhere from three to 12 years in training. The first year - the internship - is considered the most intense.

Thirty-four Brown University Medical School pediatric residents completed standardized tests following two different schedules: a month of 44-hour work weeks in office-based clinics with no overnight duties; and a month of 90-hour work weeks, including day shifts in the hospital's wards or intensive care units, plus overnight shifts once every four or five nights.

Vigilance, Attention
Following the month of longer hours, the doctors' vigilance, attention and driving skills were found to be impaired. Their test responses were equivalent to their performance after consuming three to four alcoholic drinks following a month of lighter duties.

"This adds to the growing evidence that sleep deprivation among medical residents significantly impairs their ability to perform, although it is important to note that we did not assess performance on specific medical tasks," says J. Todd Arnedt, PhD, a sleep psychologist who is a clinical assistant professor of psychiatry and neurology at the U-M Medical School. Arnedt works in the the U-M Sleep Disorders Center and the U-M Depression Center Sleep & Chronophysiology Laboratory.

Three Hours Sleep
Sleep diaries and an automatic wrist-watch activity monitor verified that the residents on heavy work shifts got significantly less sleep per night on average than those with lighter schedules during the study period.

In the 24 hours leading up to the test days, residents on a light schedule slept an average of 6 hours and 37 minutes, compared with about 3 hours for the residents on a heavy schedule.

The residents were tested four times, in two separate sessions. Two of the tests were completed after they had worked a month of light duty without overnight shifts; the tests were given before and after they consumed three to four alcoholic drinks.

In the second session, they were tested on the day after an overnight shift that came at the end of a month of 90-hour work weeks. During this session, they were tested before and after drinking a non-alcoholic placebo beverage. Of primary interest were the tests conducted after they had drunk either the alcohol or the placebo.

Performance, Effort
The researchers asked the residents to rate their performance and effort on the tests. Ratings of impaired performance were higher following the month of heavy work shifts compared to the light schedules.

Residents also rated their effort as higher after heavy work shifts compared to the lighter shifts with alcohol.

In addition, the residents rated their levels of sleepiness. During the heavy call month, they felt more tired than during the light-call month, even after they had consumed alcohol on the light-call rotation.

They were not allowed to nap on the test day or to use caffeine after noon. All of the tests were conducted at 3 pm.

Reducing Fatigue-Related Impairment
Most of the tests took place before new work-hour restrictions were imposed by the Accreditation Council for Graduate Medical Education in 2003.

Residents now are subject to the following rules: an 80-hour weekly work-hour limit; a 24-hour limit on continuous duty time; in-house call duty no more than once every three nights; and one day in seven free from all patient care and educational obligations. All requirements are averaged over four weeks.

The new regulations are "a good initial step," Arnedt noted, "but the solution to the problem is not likely as simple as well-intentioned policies aimed at reducing work hours, which can themselves have negative ramifications," he pointed out.

"Our study, like others before it, does raise concerns about the performance of sleep deprived physicians-in-training and suggests that strategies aimed at reducing fatigue-related impairments are likely necessary," Arnedt said.

Alcohol Comparison
Arnedt and his colleagues are the first to study medical residents using the sleep deprivation and alcohol comparison model, which has been used in other populations, including truck drivers. Both sleep deprivation and alcohol consumption impair a person's reaction time, attention, judgment, control and driving ability.

In a Harvard University study published earlier this year, the authors found that interns were more likely to have an automobile crash or near-miss while driving after an extended work shift.

Arnedt's team found that skills on a driving simulator deteriorated in residents who were tested after an overnight shift in the hospital at the end of a month of heavy night work. The findings from these studies suggest that the personal safety of residents who drive home after working all night may be at risk.

"We need to continue to find simple, practical and effective strategies that hospitals and senior doctors can take to reduce sleep deprivation among residents," says Arnedt.