Highlights
In a prospective multicenter cohort across 4 French university hospitals, patients operated on by surgeons with social jet lag of 2 hours or more had a significantly higher adjusted risk of 30-day major adverse events than patients whose surgeons had less circadian misalignment.
Midsleep time variability alone was not significantly associated with adverse postoperative outcomes after multivariable adjustment.
Surgeons meeting criteria for burnout had greater social jet lag and greater midsleep time variability than those without burnout, linking sleep timing irregularity to clinician well-being as well as patient safety.
The findings extend perioperative safety research beyond sleep duration and call attention to circadian regularity as a potentially modifiable occupational health target.
Clinical Context
Fatigue in surgery has traditionally been framed in terms of total sleep loss, overnight call, long duty periods, and acute sleep deprivation. Yet modern sleep science increasingly shows that when people sleep may matter alongside how long they sleep. Circadian alignment influences vigilance, executive function, mood regulation, metabolic performance, and error propensity. Social jet lag refers to the mismatch between an individual’s internal biological timing and externally imposed social schedules, typically expressed as a difference in sleep timing between workdays and free days.
In non-surgical populations, social jet lag has been associated with poorer cognitive performance, impaired mood, obesity, cardiometabolic risk, and occupational dysfunction. However, whether this form of circadian misalignment affects surgeons and their patients has remained largely unexplored. This is clinically important because surgery depends on sustained attention, procedural precision, real-time decision-making, teamwork, and recovery from unexpected intraoperative events. Even small decrements in these domains could plausibly influence patient outcomes, particularly in complex or high-risk cases.
The new study by Pascal and colleagues addresses this gap by prospectively measuring surgeons’ sleep using actigraphy and linking sleep timing regularity in the 30 days before operations to major postoperative adverse events. It is one of the first large, objective, surgeon-level investigations of circadian irregularity and surgical outcomes.
Study Design and Methods
Design and setting
This was a multicenter prospective cohort study conducted from November 1, 2020, to December 31, 2021, across 14 surgical departments in 7 specialties at 4 university hospitals in France. The analysis was performed from January to June 2025.
Participants
The study included 7117 operations in 7117 adult patients. Exclusion criteria were age younger than 18 years, palliative surgery, incomplete operative time stamps, and surgery performed by surgeons with invalid sleep data. Procedures were performed by 38 attending surgeons. The surgeons had a mean age of 46.1 years, and 79% were male. Patients had a mean age of 55.9 years, and 54.5% were female.
Exposure assessment
Surgeons’ sleep was continuously monitored using actigraphy, an objective method based on wrist-worn movement tracking commonly used in sleep research. Sleep timing regularity during the 30 days before each operation was characterized using midsleep time, defined as the midpoint between bedtime and get-up time.
Two related but distinct circadian measures were examined:
First, social jet lag was defined as the absolute difference between midsleep time on free days and workdays. This captures how much a surgeon’s sleep schedule shifts when work constraints are removed.
Second, midsleep time variability was defined as the standard deviation of daily midsleep times. This reflects overall instability of sleep timing from day to day.
Social jet lag categories were less than 1 hour, 1 to 2 hours, and 2 hours or more. Midsleep variability was also categorized, with 60 minutes or longer representing greater irregularity.
Outcome definition
The primary outcome was the occurrence of a major adverse event within 30 days after surgery. This composite included inpatient death, prolonged intensive care unit stay, reoperation, or severe complications. Overall, 1410 of 7117 operations, or 19.8%, were followed by a major adverse event.
Adjustment strategy
The authors used mixed-effects multivariable models with a random effect for surgeons. Adjustment variables included surgeon sleep duration, midsleep time, age, sex, professional status, working hours, night shifts, patient case mix, and time of incision. The patient case-mix adjustment used a composite risk score incorporating patient comorbidities and surgical characteristics. This is an important methodological strength because it attempts to separate the effect of surgeon sleep timing regularity from baseline patient and procedural risk.
Burnout was assessed using the Maslach Burnout Inventory, allowing the study to explore the relationship between sleep timing disruption and surgeon well-being.
Key Results
Primary finding: social jet lag and patient risk
The central finding was that substantial social jet lag was associated with worse postoperative outcomes. Operations performed by surgeons with social jet lag of 2 hours or more, representing 342 operations or 4.8% of the sample and involving 7 surgeons, were associated with a significantly higher adjusted relative risk of major adverse events compared with both lower exposure groups.
Compared with surgeons whose social jet lag was less than 1 hour, the adjusted relative risk was 1.36 with a 95% confidence interval of 1.04 to 1.69. Compared with surgeons whose social jet lag was 1 to 2 hours, the adjusted relative risk was 1.45 with a 95% confidence interval of 1.12 to 1.81.
These are clinically meaningful effect sizes. A relative increase of roughly 36% to 45% in major adverse events for the highest circadian misalignment category is notable, particularly because the models adjusted for total sleep duration and several work-related variables. This suggests that sleep timing regularity may convey risk information that is not captured by sleep quantity alone.
Midsleep variability and outcomes
By contrast, midsleep time variability of 60 minutes or longer, observed in 864 operations or 12.1% of the sample and involving 20 surgeons, was not significantly associated with major adverse events after adjustment. This divergence between the two sleep metrics is important. It suggests that the specific mismatch between workday and free-day timing may be more biologically or behaviorally relevant than generic day-to-day variability.
One interpretation is that social jet lag may better reflect recurring circadian phase shifts, similar to repeated mini time-zone changes, which could produce cumulative impairment in attention, mood, and recovery. Daily variability may be noisier and may include both benign and harmful patterns, reducing its predictive value.
Burnout associations
Surgeons with burnout had significantly greater sleep timing disruption than those without burnout. Median social jet lag was 75 minutes versus 52 minutes, with a P value of .04. Median midsleep time variability was 54 minutes versus 43 minutes, with a P value of .01.
These findings do not establish causality, but they align with a growing literature connecting circadian disruption to emotional exhaustion, depersonalization, and occupational strain. The study therefore points to a potentially shared pathway linking surgeon scheduling, biological rhythm disruption, clinician well-being, and patient outcomes.
How Should Clinicians Interpret These Findings?
The study should not be interpreted as evidence that individual surgeons with irregular sleep timing are unsafe in a deterministic sense, nor should it support punitive surveillance. The exposure was measured over the 30 days before surgery and analyzed at the level of associated risk within a complex system of care. Surgical outcomes emerge from the interaction of patient factors, team performance, institutional resources, procedure complexity, and perioperative processes. Even so, the findings are compelling because they suggest that circadian misalignment may be one modifiable contributor within this broader system.
For perioperative leaders, the practical message is that fitness for performance may be broader than hours slept the night before an operation. A surgeon who averages adequate sleep duration but repeatedly shifts sleep timing between workdays and free days may still experience circadian strain. This concept is familiar in other safety-critical industries, including aviation and transportation, where schedule design increasingly considers circadian physiology rather than fatigue alone.
Biological and Operational Plausibility
The observed association is biologically plausible. Circadian misalignment can impair psychomotor vigilance, reaction time, working memory, inhibitory control, and affective stability. Experimental protocols in shift-work and forced-desynchrony settings have also shown decrements in complex task performance during circadian disruption, even when sleep duration is partly preserved. In surgery, these domains map onto technical execution, anticipation of complications, communication, and decision-making under time pressure.
Social jet lag may also act as a marker of unstable work-rest organization. Surgeons with large workday versus free-day sleep shifts may be coping with early starts, variable rosters, overnight duties, and accumulated recovery debt. The adverse outcome signal could therefore reflect a combination of internal circadian misalignment and external schedule stress. The study adjusted for several scheduling variables, but residual confounding by unmeasured workload intensity, emergency burden, case complexity not fully captured by the risk score, or institutional culture remains possible.
Strengths of the Study
This investigation has several notable strengths. First, sleep was measured objectively by actigraphy rather than self-report, reducing recall bias. Second, the multicenter prospective design improves ecological validity and captures real-world surgical practice across several specialties. Third, the analysis adjusted for surgeon sleep duration, work characteristics, and patient case mix, helping isolate sleep timing regularity as an independent signal. Fourth, the use of mixed-effects models with surgeon-level random effects acknowledges clustering and repeated contributions from individual surgeons.
Another strength is the integration of surgeon burnout data. This broadens the relevance of the study beyond patient outcomes and frames circadian regularity as an occupational health issue. In modern surgical systems facing workforce strain and burnout, interventions that might benefit both clinicians and patients are particularly attractive.
Limitations and Cautions
As with any observational study, causality cannot be established. Social jet lag may be a direct contributor to poor outcomes, a marker of broader occupational stress, or both. Although the authors adjusted for many confounders, unmeasured variables could remain. For example, some surgeons with higher social jet lag may disproportionately perform more urgent, technically demanding, or resource-intensive cases in ways not fully captured by available adjustment variables.
The exposure group with social jet lag of 2 hours or more was relatively small, involving 342 operations and 7 surgeons. This raises questions about precision, center effects, and whether specific scheduling patterns within a limited subset of surgeons influenced the results. Replication in larger and more diverse cohorts will be important.
Generalizability is also uncertain. The study involved attending surgeons at French university hospitals. Results may differ in community hospitals, private systems, lower-resource settings, or among trainees. In addition, surgical teams function within anesthesiology, nursing, and institutional workflows; the sleep timing of the whole perioperative team may matter, but was not assessed here.
The primary endpoint was a composite of serious events, which improves power but may combine outcomes with different mechanisms. Future studies should examine whether social jet lag is more strongly linked to specific complications, such as reoperation, infection-related morbidity, failure-to-rescue, or prolonged ICU utilization.
Implications for Practice and Policy
The findings are hypothesis-generating but actionable enough to justify attention from departments of surgery, hospital leadership, and occupational health teams. Several low-cost strategies could be considered. These include stabilizing start times where feasible, limiting repeated transitions between early elective lists and late-night emergency activity, protecting post-call recovery, monitoring schedule volatility, and incorporating circadian health education into wellness initiatives.
Wearable-derived sleep timing metrics may eventually become useful at the program level, not to police individuals, but to identify high-risk scheduling patterns. The strongest immediate application may be system redesign rather than individual blame. If recurring social jet lag reflects avoidable schedule architecture, then organizational changes could potentially improve both workforce sustainability and patient outcomes.
These data may also influence how fatigue risk management is conceptualized in surgery. Current approaches often emphasize maximum hours, duty periods, and acute sleep loss. Circadian regularity may deserve a place beside those metrics, especially for senior surgeons who may not be captured by trainee work-hour rules but still experience substantial schedule instability.
What Research Should Come Next?
Several next steps are clear. Independent replication in other countries and health systems is essential. Studies should test whether the association persists across specialties with different emergency burdens and procedure profiles. Time-sensitive analyses could examine whether recent shifts in sleep timing, rather than 30-day averages alone, are most relevant. Team-level studies including anesthesiologists, nurses, and surgical assistants may better capture the collective circadian environment of the operating room.
Interventional research is the critical next frontier. If schedule redesign reduces surgeon social jet lag, does it improve burnout, technical performance, or patient outcomes? Pragmatic trials or stepped-wedge implementation studies could address this. Mechanistic work using simulation, intraoperative performance metrics, and biomarker-based circadian phase assessment would also help clarify causation.
Conclusion
This prospective multicenter study suggests that substantial surgeon social jet lag, defined as a 2-hour or greater difference between midsleep on free days and workdays, is associated with a higher risk of 30-day major adverse events after surgery. In contrast, broader midsleep variability alone was not significantly associated with postoperative harm. Surgeons with burnout also had more disrupted sleep timing patterns.
For clinicians and hospital leaders, the message is not that sleep quantity no longer matters, but that circadian regularity may be an overlooked dimension of surgical performance and safety. These findings expand the conversation from fatigue to biological timing. If confirmed, interventions that reduce circadian misalignment could become part of a more modern perioperative safety strategy, one that supports both the surgeon and the patient.
Funding and Registration
The abstract provided does not report a ClinicalTrials.gov registration number. Specific funding details were not included in the supplied summary and should be verified in the full JAMA Surgery article.
References
Pascal L, Polazzi S, Skinner SC, Lifante JC, Mazza S, Duclos A, TopSurgeons Study Group. Surgeon Social Jet Lag and Patient Risk of Major Adverse Events. JAMA Surgery. 2026-06-03. PMID: 42234451.
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