The effects of resident work hours on well‐being, performance, and education: A review from a Japanese perspective

Abstract This article examines the impact of working‐hour restrictions on the well‐being, performance, and education of medical residents in Japan. Despite Japan's plan to introduce new regulations for resident working hours by 2024, there is still an ongoing debate regarding their appropriateness. This review provides a comprehensive overview of the current regulations of resident working hours worldwide, with a specific focus on weekly hours. The varying regulations are highlighted, including the 80‐hour‐per‐week regulation in the United States and the 48‐h‐per‐week regulation in the European Union influencing other regions. The article also discusses the effectiveness of working‐hour restrictions on residents' mental health, with shorter working hours having potentially greater benefits. However, the impacts on medical safety and resident education are mixed, and further reduction in working hours must be carefully considered to avoid adverse effects. The planned changes to working‐hour limits for residents in Japan offer a unique opportunity to gain new evidence on the impact of such regulations, which will be of interest to policymakers and researchers worldwide.

commencement of the residency training system in Japan in 1968. 1,4 2004, the current clinical training system became mandatory, requiring physicians who complete 6 years of medical school and wish to become clinicians to undergo 2 years of training with the goal of acquiring basic skills and regardless of their desired specialty. 1The impetus for limiting work hours for residents in Japan stemmed from the work style reform initiated by the government in 2018. 5As part of this reform, the Japanese MHLW introduced new regulations limiting resident work hours to 80 h weekly, with a maximum shift length of 28 h. 6Although this limit is comparable to those of other countries, it is substantially longer than the maximum working hours for all workers and general physicians.Moreover, the permissible overtime level exceeds the threshold for "karoshi", which is the point at which compensation for death because of overwork is granted. 7 a result, there is an ongoing debate in Japan regarding the appropriateness of the maximum work hours for residents.
The impact of work-hour restrictions is complex and depends on various factors.A large body of literature evaluates the impact of resident work-hour restrictions (WHR), primarily in terms of resident well-being, patient safety, and resident education.Most research investigating the consequences of weekly work-hour limitations involves observational studies conducted before and after the imposition of work-hour limits.The weekly work-hour limit varies among countries, with the United States (U.S.) and Europe having set limits between 80 and 48 h weekly, respectively. 8However, there is limited literature available from Japan in this regard.
Randomized controlled trials have predominantly been conducted in the U.S. and have mainly focused on the effect of shift length, rather than weekly work hours. 9As a result of the potential impacts and differences in healthcare systems and cultures across countries, there is currently no consistent agreement on the ideal global limits for working hours.
Given the ongoing controversy surrounding resident work hours, it is important to understand the current evidence on this topic.This comprehensive review provides an overview of the literature on resident working hours, concentrating primarily on their global regulatory landscape and the influence of their limitation, with a specific emphasis on the available Japanese literature.This review aims to help Japanese and international readers consider the optimal balance of resident working hours.

| WORK-HOUR REG UL ATIONS
The regulation of work hours for residents has been predominantly enforced in the U.S., Europe, and Canada, with other nations, particularly in Asia, more recently adopting similar measures (Table 1). 8,10,11wever, Japan is scheduled to impose such regulations in April 2024.Most countries' regulations on resident work hours consist of two components: the total number of working hours (e.g., hours worked per week) and the longest continuous working hours in a shift.While the specific motivations for implementing WHR differ among nations and regions, they commonly prioritize medical safety, resident health, and workers' rights. 8This section aims to provide an up-to-date overview of the current status of resident WHR in Japan and other countries worldwide.

| Japan
In 2018, the Japanese government implemented a series of measures aimed at promoting reforms in the workforce. 4,5These reforms were primarily motivated by the decline in the working population because of falling birth rates and an aging demographic, as well as long working hours.Among the measures enacted were revisions to the Labor Standards Law, which introduced new regulations on working hours and interworking interval systems.Effective since April 2019 in large companies mainly, these new regulations have limited overtime work comprising 45 h per month and 360 h per year.In Japan, the legal working hours are 8 h per day and 40 h weekly, with any hours worked beyond these considered overtime.Prior to these regulations, there was no limit for overtime work hours in Japan.
Notably, the enforcement of the working-hour reform for physicians (including residents) was postponed until 2024 because of the unique nature of their profession.To ensure the effectiveness of the healthcare system, the MHLW's Study Group on Working Hour Reform for Doctors has suggested setting a standard limit of 960 overtime hours per year for physicians, with the option for longer working hours in specific cases and proposing extended working hours for physicians involved in community medicine, emergency medicine, and those undergoing training. 6,12As a result, a bill on the reform of physicians' working practices (the Medical Care Act) came The details of the execution of this reduction remain undetermined.

| The United States
In the U.S., a medical incident that occurred in New York in 1984, known as the Libby Zion case, triggered the implementation of regulations on resident work hours. 13This incident involved the unfortunate death of an 18-year-old woman as a result of a resident's medical error and brought attention to the arduous working conditions that residents face.In the aftermath, several studies were conducted and reported that prolonged working hours are associated with increased risks of medical accidents and errors. 14,15In response to these findings, the Accreditation Council for Graduate Medical Education (ACGME) introduced a regulatory measure in 2003 to limit the working hours of residents to 80 h weekly and 30 h consecutively (24 h plus 6 h for transitions of care and education). 16 2011, additional restrictions were imposed, restricting continuous duty hours to 16 h for first-year residents, while second-year residents and above were limited to 28 h (24 h plus 4 h).After randomized controlled trials demonstrated minimal effects on medical safety and resident burnout with relaxed continuous duty hours, 17,18 the ACGME conducted a study in 2017 to evaluate the impact of the new regulations on first-year residents, allowing them to work for up to 28 consecutive hours (24 h plus 4 h). 19,20

| European union
The European Working Time Directive (EWTD) has been in place since 1998, restricting working hours to ensure the health and safety of workers across all occupations in the European Union (EU).The law limits working hours to 48 h weekly, with a minimum of 11 h of rest within a 24-h period. 8,10Nevertheless, the degree of resident compliance with the EWTD guidelines varies in each country and has not been consistently reported.In some cases, residents can choose to opt out of the EWTD regulations, allowing them to exceed the 48-h weekly limit.

| Canada
There are no nationwide regulations or laws governing resident working hours in Canada. 21Instead, some provinces consult with provincial governments and resident unions to set guidelines for resident working hours.2][23] Quebec has also instituted a limit of 16 consecutive hours per week, while other provinces have established 24 consecutive hours.Each province has its own specific regulations regarding rest periods and overtime calls.

TA B L E 2
Work-hour regulations among Japanese physicians.

Implementation year
All Note: This table provides an overview of work-hour regulations in Japan, which were obtained from a reliable source cited in reference. 3The table distinguishes between different types of physicians, with Levels B and C being exclusively carried out at designated hospitals.It is worth noting that Level B is scheduled to be eliminated in 2035, while the details of the reduction for Level C are yet to be determined.

| Asia
Concerns about extended working hours for resident physicians in South Korea led to the implementation of a law in 2015 aimed at improving their working conditions and status.The legislation mandates a maximum of 80 working hours weekly and 36 h continuously. 24A survey conducted by the Korean Intern Resident Association indicated a decline in weekly working hours from 114 to 88 h between 2016 and 2019, which led to increased satisfaction with training. 24e Ministry of Health and Welfare in Taiwan introduced guidelines for resident working conditions in 2013. 25The guidelines specified a limit of 88 weekly working hours, with a maximum of 32 h consecutively and a 10-h interworking interval.Further regulations were implemented in 2018, capping weekly working hours at 80 h and mandating that residents take 1 day off per week. 26Moreover, since 2019, residents have been protected under the Labor Standard Act, which limits their work hours, ensures a regular day off, and provides flexibility in arranging their own working schedules.

| WORK HOUR AND REL ATED OUTCOME S
Residents' working hours have decreased in the past two decades, primarily in Europe and the U.S., with other countries following suit with the primary objective of safeguarding medical safety and resident well-being 8 ; however, the efficacy of such measures has yielded mixed results. 9Moreover, some studies have suggested that WHRs may have a negative impact on resident education and patient care.
Most high-quality intervention studies have concentrated on interventions for single-shift lengths instead of total hours worked per week, and there is limited evidence to determine the appropriate weekly hours worked.Nonetheless, these findings offer valuable insights for Japan, which will implement WHRs in 2024.This section provides a synopsis of the consequences of working-hour limitations, with specific emphasis on weekly hours, for resident health, performance, and education.

| Well-being
Extended work hours and excessive workload have been linked to adverse health effects, including mental disorders (e.g., depression and burnout), sleep disorders, cardiovascular diseases, and suicide. 7,27,28Residents' health is primarily evaluated through psychological assessments.Research indicates that residents experience higher levels of stress and burnout than attending physicians, particularly during the transition from student to resident. 29,30While burnout is the primary outcome measured when assessing the impact of work hours and its limitations on resident well-being, studies have also examined factors such as depression, sleep quality, and overall quality of life.
The 80-h limit on workweeks, primarily in the U.S., is likely to have a positive effect on mental health by mitigating burnout.In 2011, a systematic review showed that five out of eight studies examining the impact of the WHR introduced in the US in 2003, resulted in decreased burnout levels, particularly emotional exhaustion. 31Martini et al. 32 discovered a reduction in burnout levels from 77% to 43% among postgraduate year 1 (PGY-1) residents after the implementation of the 2003 WHR.They also reported that, before the implementation of the WHR, those working more than 80 h weekly had higher burnout rates compared to those working less (69.2% vs. 38.5%). 335][36] Although these early pre-and post-intervention studies were limited in size, with fewer than 200 participants, subsequent large observational studies and studies conducted in other countries have validated these findings.
For instance, Ogawa et al. 37 found that in a sample of 1241 firstyear residents in Japan, those working 80-100 h weekly, or more than 100 h weekly, had three and seven times higher risk of developing depressive symptoms, respectively, compared to those working 60 h.In a large cross-sectional study of 6000 residents in Japan published in 2022, working more than 90 h weekly was associated with a higher prevalence of burnout and depressive symptoms. 38[41] Two key points warrant attention regarding the impact of weekly work hours on mental health.First, the widely implemented 80-h-per-week limit may not represent the optimal threshold.Al-  42 and reported a link between longer working hours and a gradual increase in depressive symptoms, evaluated using the PHQ-9 questionnaire.Among the interns who worked more than 90 h weekly, the increase in symptom scores was three times higher than that among those who worked 40-45 h weekly.Second, interventions on shift length may have less of an impact on residents' wellbeing and mental health, as suggested by a 2015 systematic review that reported their ineffectiveness in enhancing overall well-being. 43is is further supported by the results of two subsequently conducted randomized controlled trials, indicating that extending shift length did not exacerbate resident burnout. 17,44These results were significant enough to prompt a regulatory change in the U.S., which led to the deregulation of shift length of PGY-1 residents in 2017.

| Performance
6][47] One study suggests that chronic sleep deprivation of 6 h or less is equivalent to 2 days of total sleep deprivation in terms of cognitive performance deficits. 47Despite expectations that limiting work hours would increase patient safety and improve medical outcomes, the available evidence is insufficient to support the conclusion that WHRs enhance medical safety, as study findings have been inconclusive. 10,48e lack of published studies examining the association between residents' work hours and medical errors was unexpected.Landrigan et al. ( 2004) conducted a randomized controlled trial that compared 30-and 16-h shifts for intensive care unit interns. 15The intervention resulted in a reduction of 15-20 work hours weekly (77-81 vs. 63 h) and a corresponding 5.6-fold increase in medical errors among interns on the 30-h shift schedule.Similarly, a study conducted in the UK evaluated interns working under a 48-h-per-week limit and found that the intervention group working 48 h or less weekly had a significantly lower likelihood of committing errors than the control group working 56 h or less weekly. 49Conversely, a US-based prospective cohort study examining the impact of work-hour restrictions on pediatric residents found no significant changes in their sleep or work hours, or their drug prescription or self-reported medical errors. 50Moreover, a cross-sectional study investigating self-reported practice errors among internal medicine residents found no association between an 80-h workweek limit and suboptimal care or medical errors. 51ltiple systematic reviews have shown that implementing work hour restrictions for residents (2003 WHR) is associated with a decrease in patient mortality. 31,52For instance, Fletcher et al. ( 2011) conducted a meta-analysis and found that the odds ratio of patient death decreased to 0.9 (95% Confidence Interval [CI]: 0.84-0.95)after the implementation of 2003 WHRs compared to the before. 31wever, the interpretation of these findings should be approached with caution.Baldwin et al.'s 52 systematic review in 2011 indicated that there were no significant differences in patient mortality before and after 2003 WHRs among the teaching hospital and the nonteaching hospital groups.Thus, the reduction in mortality rates may not be a direct consequence of resident WHRs but may be influenced by other factors such as technological advancements, promotion of a culture of medical safety, and improved levels of physician practice.
Investigations have also been undertaken regarding the effect of WHRs on complications, with systematic reviews presenting inconclusive findings. 31,52,53Conversely, a systematic review conducted in 2014 on surgical residents revealed a potential escalation in complications and even increasing mortality as well. 53In 2017, a large cohort study documented 110 million hospitalizations before and after the enforcement of the 2003 WHRs and showed that inpatient complications surged, particularly in teaching hospitals, with a reported increase of 10%. 54A study comparing surgical patients before and after 2003 WHRs found a significant reduction in provider-related complications (48% vs. 39%). 55

| Education
The primary objective of implementing WHRs is to enhance the working conditions of residents and improve patient safety.
However, supervisors and residents have raised concerns regarding the potentially negative implications of these measures on educational aspects.The impact on education has been objectively measured through various parameters such as training opportunities, number of case experiences, and examination performance. 31,53,56substantial body of research has scrutinized the impact of WHRs on the number of case experiences, with a specific focus on the surgical experience of surgical residents.Several studies have established that resident caseloads either decrease or remain unchanged.A systematic review conducted in 2011 examined the impact of work-hour restrictions on caseloads and found that out of 37 studies, 11 (30%) revealed a reduction in surgical experience, while 25 showed no significant change. 56Out of the 11 studies that demonstrated a decrease in surgical experience, six were conducted in the U.S. and five in the U.K., implying that a less than 80-h-per-week limit, whether a 48-or 56-h limit, could result in a decrease in case experience.However, the sample sizes of these studies were relatively small, and the observations were short-term.A significant study published in 2013 analyzed ACGME case logs in general surgery and reported that the number of surgical cases declined temporarily after the 2003 WHRs but subsequently recovered. 57Similarly, a 2014 study on thoracic surgery revealed no significant change in the number of cases before or after the work-hour restriction. 58mited data are available on whether surgical experience has recovered in the UK or Europe, but it is plausible that the 80-h work week may have had a negligible impact on surgical experience.Additionally, a U.S. study that surveyed surgical residents' opinions following the 2003 WHRs found a decrease in case experience but an increase in reading time. 59This finding suggests that the quality of education might have been maintained through the acquisition of knowledge from sources other than direct medical experience.
The effect of the 80-h work-week restriction on exam scores has been primarily studied in the U.S., and it appears that it does not necessarily worsen scores.According to a 2011 systematic review, out of 10 studies that evaluated in-training exam scores, two reported improvement, two reported worsening, and the remaining six found no significant differences. 31Moreover, a 2014 study that analyzed the U.S. Internal Medicine Board Examination showed no significant change before or after the implementation of the 2003 WHRs. 60A recent cross-sectional study conducted in Japan, 61 involving 5500 residents, revealed that resident in-training exam scores tended to decrease when residents worked less than 60-65 h weekly and did not improve when residents worked longer.This result suggests that decreasing work hours to 60 h weekly rather than 80 may have a limited effect on exam scores.
The influence of WHRs on other educational outcomes has also been examined.Investigations on the effects of the 2003 WHRs on U.S. internal medicine residents have revealed limited engagement in educational activities. 34,62Conversely, Jagsi et al. 63

| FUTURE DIREC TIONS
According to Level C-1 regulations in Japan, the maximum weekly working hours for residents will be limited to 80 h weekly starting in April 2024.This is in line with the work-hour limit observed in the U.S., and findings from the U.S. context may be applicable to Japan.The implementation of this regulation is anticipated to have a favorable impact on the well-being of residents; however, it may have adverse consequences for education (Figure 1).Concerns have been raised about the educational implications, especially in relation to the reduction of case experiences, particularly in surgical settings, which has been noted in other countries.Nonetheless, the impact of such limitations may be limited in Japan as residents receive uniform training aimed at obtaining standard basic clinical skills unrelated to their specialty.
The effect of restricting work hours on the occurrence of practice errors is uncertain and may not yield the desired outcomes.Positive and negative effects on mortality and morbidity have been demonstrated.
However, the degree of responsibility of Japanese residents for their practice is limited, potentially rendering these effects insignificant.It is important to acknowledge that the purpose and realities of resident training vary across countries, which presents limitations when applying research from other countries to Japan.Therefore, it will be necessary to evaluate the impact of work-hour limitations in Japan and make future improvements based on the results.
Although the exact percentage remains unclear, a considerable number of Japanese residents are expected to be subject to Level A regulations.The work week restriction of 60 h weekly is comparable to that in Europe, and there is considerable uncertainty regarding its potential impact.Research has indicated that there may be a dose-response relationship between working hours and resident well-being and that even greater improvements in well-being may be achieved with limits below 80 h weekly.

F I G U R E 1
The potential impact of resident duty hour regulations versus to no regulations in Japan.Japan is poised to implement working-hour restrictions for both physicians and residents in April 2024.The upcoming regulations will mandate different weekly workinghour limits for residents based on their categorization as either Level C-1 or Level A. Level C-1 residents will be subject to a maximum weekly working-hour threshold of 80 h in consideration of their current workload, whereas Level A residents and all physicians will be subject to a standard weekly limit of 60 h.

| CON CLUS ION
The Japanese government announced its intention to implement

CO N FLI C T O F I NTE R E S T S TATE M E NT
The authors declare that no conflicts of interest exist.

E TH I C S S TATEM ENT
None.

R E FE R E N C E S
It is crucial to examine residents in specialty training (PGY-3, 4, and 5) when evaluating the effects of resident work-hour limitations in Japan.The introduction of a new physician specialty training system in 2018 mandated a minimum of 3 years of specialized training for physicians seeking to acquire a subspecialty.66These residents may be subject to Level C regulations similar to those of medical residents (PGY-1 and 2).However, residents in specialty training require more specialized and rigorous training and are entrusted with a significant number of decision-making and patient care responsibilities.As such, there is a heightened concern regarding the impact of work hours on education and patient care performance.As a result of the highly individualized nature of each specialty in setting appropriate working hours, it is crucial to secure the cooperation of each specialty's associated societies.
weekly work-hour restrictions for residents in 2024.The restrictions involve a combination of 80-and 60-h weekly limits for each training hospital.While these measures are anticipated to enhance residents' well-being and work-life balance, there is apprehension that strict work-hour limitations may compromise the quality of resident education and patient care.Despite the global acceptance of the 80-h-per-week threshold following its introduction in the U.S., the incorporation of dual work-hour restrictions in Japan is expected to represent a significant social demonstration experiment.Comprehensive studies examining the impact of work-hour limitations in Japan could provide pivotal evidence for other countries to devise appropriate working-hour limits.

TA B L E 1 Work-hour regulations in Japan and worldwide. Country Regulation source Maximum weekly working hours Maximum continuous working hours Implementation year Reference
65und that WHRs did not significantly diminish case or procedural experience, or sense of clinical preparedness among 1770 residents, despite a decrease in patient care hours from 48.5 to 42.3 h.Edson et al.64reported a negligible impact on residents' learning time resulting from work-hour restrictions.Meanwhile, a large national observational study conducted in Japan found that resident self-study time was shorter for those working less than 60 h per week compared to those working 60-65 h per week, and there was no significant increase in self-study time for those working over 65 h per week.65 37,42However, there is concern that resident education may be negatively affected, as previous research indicates that less than 60 work hours weekly may lead to decreased in-training examination scores and less self-study time.
portunities.While decreased fatigue and sleep deprivation may lead to expected improvements in decreasing the incidence of medical errors, there is a possibility that the number of residents exhibiting suboptimal medical skills may increase, and this outcome warrants further investigation.