Sleep, Well-Being, and Cognition in Medical Interns on a Float or Overnight Call Schedule
Authors: Stijn A. A. Massar, Xin Yu Chua, Ruth Leong, Hosein A. Golkashani, Zhenghao Pu, Alyssa S. C. Ng, Ju Lynn Ong, Chun Siong Soon, Nicholas B. H. Ng, Mae Yue Tan, Jeremy B. Lin, Marion Aw, Michael W. L. Chee
Journal: JAMA Network Open (2024)

Importance Extended work hours and night shifts are essential in health care, but negatively affect physician sleep, well-being, and patient care. Alternative schedules with shorter work hours and/or reduced irregularity might mitigate these issues. Objective To compare sleep, well-being, and cognition between interns working irregular, extended shifts (call schedule), and those working a more regular schedule with restricted hours (float schedule). Design, Setting, and Participants In this observational longitudinal cohort study, interns in a Singapore-based teaching hospital were studied for 8 weeks from January 2022 to July 2023. Data were analyzed from July 2023 to July 2024. Exposure Participants worked either regular approximately 10-hour workdays, interspersed with 24 hour or more overnight calls 4 to 5 times a month, or a float schedule, which included regular approximately 10-hour workdays, and 5 to 7 consecutive approximately 12-hour night shifts every 2 months. Exposure was based on departmental training and operational needs. Main Outcomes and Measures Sleep was measured with wearable sleep trackers and an electronic diary. Day-to-day well-being and cognitive assessments were collected through a smartphone application. Assessments included the Sleep Regularity Index (SRI; determines the probability of an individual being in the same state [sleep or wake] at any 2 time points 24 hours apart, with 0 indicating highly random sleep patterns and 100 denoting perfect regularity) and Pittsburgh Sleep Quality Inventory (PSQI; scores ranges from 0 to 21, with higher scores indicating poorer sleep; a score greater than 5 suggests significant sleep difficulties). Results Participants (mean [SD] age, 24.7 [1.1] years; 57 female participants [59.4%]; 41 on call schedule [42.7%]; 55 on float schedule [57.3%]) provided 4808 nights of sleep (84.2%) and 3390 days (59.3%) of well-being and cognition assessments. Participants on a float schedule had higher SRI scores (mean [SD] score, 69.4 [6.16]) and had better quality sleep (PSQI mean [SD] score, 5.4 [2.3]), than participants on call schedules (SRI mean [SD] score, 56.1 [11.3]; t 91 = 6.81; mean difference, 13.3; 95% CI, 9.40 to 17.22; P &amp;amp;lt; .001; PSQI mean [SD] score, 6.5 [2.3]; t 79 = 2.16; 95% CI, 0.09 to 2.15; P = .03). Overnight call shifts, but not night float shifts, were associated with poorer mood (−13%; β = −6.79; 95% CI, −9.32 to −4.27; P &amp;amp;lt; .001), motivation (−21%; β = −10.09; 95% CI, −12.55 to −7.63; P &amp;amp;lt; .001), and sleepiness ratings (29%; β = 15.96; 95% CI, 13.01 to 18.90; P &amp;amp;lt; .001) and impaired vigilance (21 ms slower; β = 20.68; 95% CI, 15.89 to 25.47; P &amp;amp;lt; .001) compared with regular day shifts. Night shifts with naps were associated with better vigilance (16 ms faster; β = −15.72; 95% CI, −28.27 to −3.17; P = .01) than nights without naps. Conclusions and relevance In this cohort study, 24-hour call schedules were associated with poorer sleep, well-being, and cognition outcomes than float schedules. Naps during night shifts benefited vigilance in both schedules.