How does shift work affect your health?


The immediate cons of an erratic work schedule are clear-cut: You may be tired all the time or missing out on time with loved ones.

More dire long-term consequences may also be at play, according to new research on the associations between work patterns in young adulthood and health outcomes later in life.

Multiple studies have shown how irregular work hours can harm overall health and social life, but the new paper views the relationship through a “life-course” approach, observing how work patterns affect health throughout adulthood instead of one point in time.

The new report, published Wednesday in the journal PLOS ONE, defined a standard work schedule as beginning at 6 a.m. or later and ending at 6 p.m. An evening work schedule meant starting at 2 p.m. or later until midnight, while nighttime schedules were shifts starting at 9 p.m. or later and ending by 8 a.m. Participants had “variable” schedules if they had split or rotating shifts or irregular hours. 

“About three-quarters of the work patterns we observed did not strictly conform to working stably during daytime hours throughout our working years,” said Dr. Wen-Jui Han, the sole author of the study and professor at the Silver School of Social Work at New York University, in an interview conducted by the journal.

“This has repercussions,” added Han, who specializes in social welfare policy with an emphasis on children and families. “People with work patterns involving any degree of volatility and variability were more likely to have fewer hours of sleep per day, lower sleep quality, lower physical and mental functions, and a higher likelihood of reporting poor health and depressive symptoms at age 50 than those with stable standard work schedules.”

Han also looked into how these associations depended on social position, marked by race or ethnicity, gender and education.

Despite the challenges of today’s work schedules, health experts say there are strategies people can use to mitigate the negative impacts.

Work patterns decades earlier affect health in midlife

To assess work-shift issues, Han used data from more than 7,300 participants, about 50% of whom were White, 33% Black and 19% Hispanic. They were part of the U.S. National Longitudinal Survey of Youth 1979, a nationally representative sample of Americans who were between ages 14 and 22 and surveyed at different points over time.

Working early standard hours then transitioning into volatile schedules between ages 22 and 49 was significantly associated with the poorest health, Han found. This pattern was also linked with reporting the poorest health and depressive symptoms at age 50. The size of the effect was equivalent to being educated to only below high school level, and the impacts of working volatile schedules were worse than those of having been mostly unemployed.

The study also found race- and gender-related trends, such as the higher likelihood of Black Americans having schedules linked with poorer health and for women experiencing lower-quality sleep even though they were getting more hours of sleep.

The report doesn’t have a full explanation for the disproportionate effects on women and Black people, but that finding speaks “to the intersectionality between employment patterns and social position, underscoring the substantial health disparities between those with resources and those without,” according to the study. “Those without disproportionately shoulder the adverse consequences of volatile employment patterns.”

The study results aren’t exactly “super surprising,” but they are “very timely and alarming,” said Dr. Xiaoxi Yao, a professor of health services research at the Mayo Clinic in Minnesota. She wasn’t involved in the study.

Because of the advancement in technology and the gig economy, especially since the pandemic, people are increasingly working nonstandard schedules in comparison with several decades ago, Yao said via email.

“People in higher socio-economic status might enjoy the flexibility of working from anywhere at any time, whereas people in the so-called vulnerable social positions might not have a choice,” Yao added. “We are often worried about these workers’ wages and benefits but this study calls out that the non-standard work schedules and hours might inherently put workers at risk.”

Explaining the links between shift work and health

There are several potential theories that could explain the findings, but the study itself shows only association, not causation, experts said.

“A person can have some risk factors that make it difficult to both find a stable job and more likely to develop a disease,” Yao said. “It is difficult to use the current data to draw a firm conclusion that the work schedules/hours caused the adverse health outcomes.”

But at the same time, the findings build on a growing body of evidence.

The research results are “in line with what everyone in public health knows, which is that one’s health outcomes are determined by a myriad of factors, including what work they have, since type of work determines their daily routines and, crucially, their income and therefore what resources they can access,” said CNN wellness contributor Dr. Leana Wen, an emergency physician and adjunct professor of health policy and management at the George Washington University Milken Institute School of Public Health, said via email. Wen wasn’t involved in the study.

Nonstandard schedules can make it difficult to maintain lifestyle habits important for good health — such as sleeping well, eating at regular hours and spending time with loved ones, said Dr. Azizi Seixas, associate director of the Center for Translational Sleep and Circadian Sciences at the University of Miami Miller School of Medicine, who wasn’t involved in the study.

What’s more, the financial instability of some nonstandard work can also cause anxiety, Yao said. And when this work involves working independently, the lack of a stable social environment can decrease one’s sense of belonging and identity.

Sleep researcher Dr. Christian Benedict, who wasn’t involved in the study, noted the findings may not apply to everyone.

“For example, Dr. Han’s study didn’t examine people’s natural sleep-wake cycles,” Benedict, an associate professor of pharmacology at Uppsala University in Sweden, said via email. “It is crucial to recognize that working late-night shifts might be more suitable for individuals who naturally stay up late rather than those who prefer waking up early.”

What you can do

Changing schedules or jobs to avoid nonstandard working hours may not be feasible for some, but you can use other strategies — such as healthy diet, exercise, relaxation and spending time with friends and family — to offset the potential harm from work, Yao said.

Additionally, still having some kind of routine or schedule around that shift can make it easier to fit in those health-promoting activities — especially sleep, Yao added.

Try to optimize your sleeping conditions as much as possible, such as by sleeping in a dark and cool room and asking family members to respect your sleep schedule, Benedict said.

And past research has found that refraining from eating late at night counteracts the negative effects of shift work on health, he added. Be sure to also schedule routine health checkups and seek guidance from a professional if persistent health concerns arise. 

“By incorporating these strategies into their daily lives,” Seixas said, “individuals can proactively mitigate the negative effects of nonstandard work schedules on their health and promote overall well-being despite the constraints imposed by their employment patterns.”


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