ANN ARBOR, Mich. -- The long hours and overnight shifts that are a riteof passage for young doctors may leave them so sleep-deprived that theyfunction as poorly as if they'd had a few cocktails, a new study finds.
In findings published in this week's issue of the Journal of theAmerican Medical Association, 34 young pediatric residents showedsimilar impairments in vigilance, attention, and driving skills onstandardized tests after they had been on duty overnight in thehospital and worked a month of 90-hour weeks, compared with when theyhad consumed three to four alcoholic drinks after a month of 44-hourweeks with no overnight duties.
The study involved medical residents from Brown University MedicalSchool and was led by a sleep researcher from the University ofMichigan Health System. Most subjects were tested before new nationalrequirements limited resident work hours to an average 80-hour workweek and maximum 24-hour work day.
The team monitored participants' sleep habits during the study usingsleep diaries and an automatic wrist-watch activity monitor, whichverified that the residents on heavy work shifts got significantly lesssleep per night on average than those with lighter schedules.
They also asked the residents to rate their performance and effort onthe tests. Ratings of impaired performance were higher following themonth of heavy work shifts compared to the light work shifts andresidents rated their effort as higher after heavy work shifts comparedto the light work shifts with alcohol.
"This adds to the growing evidence that sleep deprivation among medicalresidents significantly impairs their ability to perform, although itis important to note that we did not assess performance on specificmedical tasks," says J. Todd Arnedt, Ph.D. a sleep psychologist who isa Clinical Assistant Professor of Psychiatry and Neurology at the U-MMedical School.
"The regulations in place that limit the number of hours residents canwork each week on average are a good initial step, but the solution tothe problem is not likely as simple as well-intentioned policies aimedat reducing work hours, which can themselves have negativeramifications. Our study, like others before it, does raise concernsabout the performance of sleep deprived physicians-in-training andsuggests that strategies aimed at reducing fatigue-related impairmentsare likely necessary."
Arnedt and his colleagues are the first to study medical residentsusing the sleep deprivation and alcohol comparison model, which hasbeen used in other populations including truck drivers. Both sleepdeprivation and alcohol consumption impair a person's reaction time,attention, judgment, control and driving ability.
The residents were tested four times, in two separate sessions. Two ofthe tests were done after they had worked a month of light duty withoutovernight shifts; the tests were done before and after they consumedthree to four alcoholic drinks. In the second session, they were testedon the day after an overnight shift that came at the end of a month of90-hour work weeks that included overnight work every fourth or fifthnight. During this session, they were tested before and after drinkinga non-alcoholic placebo beverage. The main comparison of interest werethe tests conducted after they had drunk either the alcohol or theplacebo.
In a Harvard University study published earlier this year, theauthors found that first-year residents (called interns) were morelikely to have an automobile crash or near-miss while driving after anextended work shift. Arnedt and his colleagues found that skills on adriving simulator deteriorated in residents who were tested after anovernight shift in the hospital and at the end of a month of heavynight work. The findings from these two studies suggest that thepersonal safety of residents who drive home after working all night maybe at risk.
The new U-M/Brown study compared residents who were workingdays in office-based clinics for about 44 hours a week with those whowere working up to 90-hour weeks of day shifts in the hospital's wardsor intensive care units, and also had to be in the hospital and awakeovernight once every four or five nights to care for patients. (Inhospital jargon, a resident who has just completed a period of suchintense duty is said to be "post-call.")
Depending on the type of medical or surgical care they decide tospecialize in, young doctors can spend anywhere from three to twelveyears in residency and fellowship training. The first year, called theinternship, is considered the most intense and also features morerotation between different sub-specialties and hospital wards.
Arnedt hopes that this growing body of research on the effects of sleepdeprivation among residents helps to highlight the consequences ofinadequate sleep in medical training. In 2003, the AccreditationCouncil for Graduate Medical Education imposed an 80-hour weeklywork-hour limit, a 24-hour limit on continuous duty time, in-house callduty no more than once every three nights, and one day in seven freefrom all patient care and educational obligations, all averaged overfour weeks.
"We need to continue to find simple, practical, and effectivestrategies that hospitals and senior doctors can take to reduce sleepdeprivation among residents," says Arnedt, who hopes to study suchstrategies in future. "We also need to continue to study this issue inother types of residents." Arnedt is a member of the the U-M SleepDisorders Center, and the U-M Depression Center Sleep &Chronophysiology Laboratory.
For now, though, the new JAMA paper quantifies the issue further, withclear results that contrast with some previous studies whosemethodologies did not allow for clear interpretation.
For example: The reaction time of residents who had just finished amonth of heavy work schedules was 7 percent slower and they committed40 percent more errors than when they were on a month of lightschedules, On a driving simulator, they had more difficulty maintaininga consistent lane position and a constant speed during the heavy workcompared to the lighter work schedule. Speed variability on the drivingtest was also 29 percent higher following the heavy-schedule comparedto the light schedule after drinking alcohol, but there were no otherperformance differences between these two conditions.
In other words, after a month of 90-hour weeks with overnight shiftsevery fourth or fifth night, residents performed about the same as whenthey had a BAC of 0.04 percent after a month of 44-hour weeks ofdaytime shifts.
The sleep monitoring performed for the study used a wrist device calledan actigraph, which records the wearer's level of movement and allowsresearchers to download data into a computer to assess how many hours aperson was inactive, which is used as a proxy measure of sleep.
In the 24 hours leading up to the test days, residents on a lightschedule slept an average of 6 hours and 37 minutes, compared withabout 3 hours for the residents on a heavy schedule. Residents'post-call ratings of sleepiness during the heavy call month were alsohigher than their ratings during the light call month, even after theyhad consumed alcohol on the light call rotation. Residents were notallowed to nap on the test day or to use caffeine after noon time. Boththe light-duty and post-call tests were conducted at 3 p.m.
The researchers asked the residents to rate their performance on thedriving, attention and vigilance tests, from poor to very good. Theythen correlated those self-ratings with the residents' actualperformance. In general, the residents who had just completed heavywork schedules could judge their own performance, but only modestly .
In addition to Arnedt, who moved from Brown to U-M in 2004, the study'sauthors include his two sleep-research colleagues from Brown: JudithOwens, M.D., MPH and Mary Carskadon, Ph.D. Research assistants MeganCrouch and Jessica Stahl are co-authors. The study was funded by agrant from the American Academy of Sleep Medicine.
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