CHAMPAIGN, Ill. — Workers who juggle volatile work hours that change from week to week may experience adverse health effects that impact their ability to work, although the limitations vary by gender, say researchers at the University of Illinois Urbana-Champaign who conducted a recent study. Men who experienced greater fluctuations in their work hours were more likely to report worsening health but remain in their jobs, while women tended to reduce their hours, suspend work or leave their jobs entirely for health-related reasons, according to the study's authors, doctoral student Sinyee Qianyi Lu and sociology professor Tim Liao .
The researchers examined data on more than 61,000 U.S. workers ages 18-64 who participated in the Current Population Survey, a monthly household survey that is administered jointly by the U.S. Census Bureau and the U.S. Bureau of Labor Statistics. Participants' self-rated health status and their month-to-month work hours were tracked across a 16-month period to study interactions between the two.
Published in the journal SSM – Population Health, the findings add to a growing body of research examining the health consequences of unstable work time and schedules, including substantial fluctuations in weekly work hours. By including data on workers who decreased their work hours, interrupted or terminated employment due to health strains — a group that prior studies often excluded — the current study lends greater clarity to our understanding of the health effects associated with precarious employment and men's and women's differing responses to adverse working conditions, the researchers said.
"Job quality matters and involves not only pay, benefits or total hours, but also the work schedule stability and resulting health outcomes — an area that has been underexplored in much of the prior research," said Lu, who
studies occupational inequality, nonstandard scheduling and the rise of remote/hybrid work. "By treating health-related work limitation as an outcome rather than sample attrition, our analysis followed these individuals even when their deteriorating health caused them to reduce or exit paid employment. Making health-driven employment changes observable matters because these individuals shape who remains in the employed population and what health effects are detectable. Expanding the sample beyond the continuously employed 'survivors' brings into focus the broader population that is also at risk," Lu said.
The researchers obtained data from the Current Population Survey basic monthly files and the CPS Annual Social and Economic Supplements obtained from the University of Minnesota's Integrated Public Use Microdata Series. By linking individuals' data at specific time points across these two datasets, the researchers were able to track participants' work hours and health changes across two consecutive calendar years.
The project encompassed two four-month observation periods two years apart, separated by an eight-month unobserved interval. Spanning the periods 2016-2018 and 2020-2024, the overall sample encompassed the prepandemic, midpandemic and postpandemic years.
In the baselined model, there were 55,062 continuously employed individuals, and the expanded model reintroduced 6,069 additional people who reported health-related work limitations during the second year they were studied for the current project. Those in the latter group reported working part-time for health reasons, being absent from work because of illness or medical problems, or having left the workforce entirely due to illness or disability, Lu said. She and Liao examined not only whether instability in work hours shaped workers' health, but also whether the level of weekly hours worked made an impact and if these effects differed by gender.
During monthly interviews, a part of the CPS supplements, respondents rated their health status from excellent to poor. The researchers tracked subsequent changes to their self-ratings, coding them into four outcome categories — improved health, stable health, deteriorated health or health-related work limitations.
Among men, the evidence suggested that greater volatility in working hours was associated with a gradual decline in self-rated health — particularly among those working greater weekly hours — although they remained employed, according to the researchers.
The team found that the predicted probability of health deterioration among men rose steadily with work-hours volatility, increasing from 28% with no changes in work hours to 38% with extremely large fluctuations in hours between months. Likewise, the probability of stable health declined steadily, from about 46% to 38%, while the predicted probability of improved health changed little.
"It's quite loud and clear that it's not about the absolute amount of work hours," Liao said. "Having either stable hours of 40 or 25 per week throughout makes no difference in terms of the volatility index — nor does the absolute amount of change. The problem is more with the proportional change — one week up, next week down. Perhaps people can adjust to the total amount of change, but not to the sudden ups and downs. That's a different story."
For those women who remained employed, the researchers found no clear patterns. Volatility was neither significantly associated with self-rated health deterioration or improvement. Women's outcomes only became visible when health-related work limitations were included as an outcome, the researchers said.
"The gender-stratified modeling we created in this study confirms sharp differences in the health pathways for men and women: Volatility in employees' work hours is reflected in on-the-job health deterioration among men — especially at higher weekly work hours — and in health-related work limitations or withdrawal from active employment by women," Lu said. "Instability in work hours is not merely a scheduling inconvenience but a gendered, population-level health risk, and that's why we should care about it."
