The effects of on-duty napping on intern sleep time and fatigue

Background: Naps during extended work shifts are effective in reducing fatigue in other industries, but the use of a nap as a countermeasure to prevent fatigue in residents is uncertain. Objective: To assess the effects of a call-night nap on resident sleep and fatigue. Design: 1-year, within-participant, paired trial with crossover at midmonth. Setting: Academic teaching hospital. Participants: 38 of 40 internal medicine interns. Measurements: Sleep was measured by using wristwatch actigraphy. By using the experience sampling method on a personal digital assistant, random alerts prompted interns to rate fatigue on the 7-point Stanford Sleepiness Scale (7 is most tired). Hospital paging logs and structured interviews provided information on use of coverage. Intervention: For 2 weeks of every month, interns were assigned to the nap schedule, which provided coverage to on-duty interns from midnight to 7:00 a.m. so that they could finish their work and take a nap. The other 2 weeks of the month constituted a standard schedule. Results: Interns received 41 more minutes of sleep while on call with the nap schedule (185 minutes vs. 144 minutes; P < 0.001). When interns with the nap schedule used coverage, they received 68 more minutes of sleep (210 minutes vs. 142 minutes; P < 0.001). Despite these small increases in sleep, interns reported less overall fatigue while on the nap schedule than while on the standard schedule (1.74 vs. 2.26; P = 0.017). Postcall fatigue with the nap schedule was lower by nearly 1 point (2.23 vs 3.16; P = 0.036), which is almost equivalent to the difference between oncall and postcall fatigue with the standard schedule (2.06 vs. 3.16). However, use of coverage by interns on the nap schedule was impaired by their desire to care for their patients and concerns about discontinuity of care. Limitations: This was a single-institution study that did not have the power to examine outcomes related to intern or patient wellbeing. Conclusions: Coverage to allow a nap during an extended duty-hour shift can increase sleep and decrease fatigue for residents.