HealthDay News — New interns’ intense and changing schedules take a toll on sleep, activity, and mood, according to a study published online March 14 in the Journal of General Internal Medicine.
David A. Kalmbach, Ph.D., from University of Michigan in Ann Arbor, and colleagues evaluated how the residency experience affects sleep, physical activity, and mood among 33 first-year residents. Data were collected for two months pre-internship through the first six months of internship.
The researchers found that after beginning residency, interns lost an average of two hours and 48 minutes of sleep per week (P < 0.01). Mood and physical activity decreased by 7.5 and 11.5 percent, respectively (both P < 0.01). A bidirectional relationship emerged in which short sleep predicted worse mood the next day (P < 0.001), which, in turn, predicted shorter sleep the next night (P = 0.03). Short-term sleep’s effect on mood was twice as large as mood’s effect on sleep. Additionally, substantial shifts in sleep timing during internship (sleeping at least three hours earlier or later than pre-internship patterns) led to shorter sleep (earlier: P < 0.01; later: P < 0.001) and poorer mood (earlier: P < 0.001; later: P < 0.001).
“Shift work, short sleep, and physical inactivity confer a challenging environment for physician mental health,” the authors write. “Efforts to increase sleep opportunity through designing shift schedules to allow for adequate opportunity to resynchronize the circadian system and improving exercise compatibility of the work environment may improve mood in this depression-vulnerable population.”