Night float vs Call: Study reveals impact on medical interns’ sleep and performance
A new study suggests that medical interns working on float schedules with concentrated night shifts experience better sleep regularity, mood, and cognitive performance compared to those on traditional call schedules with extended shifts.
Research findings
A cohort study conducted at a Singapore teaching hospital has revealed that medical interns working on a float schedule, characterised by consecutive 12-hour night shifts, experienced more regular sleep patterns and better self-reported sleep quality compared to those on a traditional call schedule with 24-hour shifts. The study, published 11 October 2024 in JAMA Network Open, tracked 96 first-year postgraduate physicians over an eight-week period, measuring sleep, well-being, and cognitive performance.
The researchers employed wearable sleep trackers and smartphone-based assessments to gather data on sleep patterns, mood, motivation, and cognitive function. They found that interns on the float schedule had significantly higher sleep regularity scores and reported better sleep quality than those on the call schedule.
Notably, day-to-day mental well-being and cognitive assessments were relatively unaffected after night float shifts, whilst 24-hour overnight call shifts were associated with poorer sleep and well-being ratings, as well as impaired cognitive performance, particularly in working memory and vigilance tasks.
Impact on sleep regularity
The study highlighted the importance of sleep regularity, which is increasingly recognised as a crucial factor in health and well-being. Dr Stijn A. A. Massar, the lead author of the study, noted: “Although the call group in our study had equal or longer sleep duration compared with the float group, their sleep schedule was characterised by higher sleep irregularity.”
This finding is particularly significant as sleep irregularity has been associated with mental health issues in both the general population and physicians. Long-term consequences of high sleep irregularity include increased risks of cardiovascular disease, hypertension, and premature death.
Impaired cognition and medical errors
The study revealed that daily ratings of mood, motivation, and sleepiness were worse after an overnight call shift. Dr Massar explained: “This triad has been associated with an individual’s readiness to perform in relation to the prior night’s sleep duration and could affect learning and interpersonal interactions.”
Importantly, objective assessments of working memory and vigilance were also relatively poorer after overnight calls. The researchers noted that impaired working memory has been associated with medical errors in the face of sleep loss, while impaired vigilance relates to missing critical signals and involuntarily falling asleep.
Benefits of napping
An interesting finding from the study was the potential benefit of on-shift napping. The researchers found that vigilance performance was better after night shifts that included a nap compared to those without. This suggests that strategic napping during night shifts could help mitigate some of the negative effects associated with extended work hours.
Implications for medical training
While the study did not directly measure patient outcomes or educational outcomes, it provides valuable insights into the potential benefits of float schedules for medical interns. Dr Michael W. L. Chee, the corresponding author, commented: “Our findings suggest that a float schedule may have fewer negative outcomes for sleep, well-being, and cognition than a call schedule.”
The researchers acknowledged that long duty hours have been suggested to allow for more professional education and potentially decrease adverse patient outcomes arising from more frequent handoffs. However, they cited a recent study in Singapore that found no significant differences in learning attainment or patient safety between different scheduling systems.
Limitations and future directions
The authors noted several limitations to their study, including its observational nature and the inherently different work requirements between medical departments. They suggested that future research could benefit from randomised controlled trials to establish causal relationships between scheduling systems and outcomes.
Despite these limitations, the study provides compelling evidence for the potential benefits of float schedules in medical training. As healthcare systems continue to confront the challenge of balancing patient care, medical education, and physician well-being, these findings offer valuable insights for shaping future policies and practices in medical internship programmes.
Reference
Massar, S. A. A., Chua, X. Y., Leong, R., et. al. (2024). Sleep, Well-Being, and Cognition in Medical Interns on a Float or Overnight Call Schedule. JAMA Network Open, 7(10), e2438350. doi: https://doi.org/10.1001/jamanetworkopen.2024.38350
