UCLA Fielding-led research links shift work to higher risk of death among U.S. workers with cardiometabolic diseases

A recently published study by an international team led by researchers with the UCLA Fielding School of Public Health has connected working swing or night shifts with higher risk of death among U.S. workers with cardiometabolic diseases.

“The current secondary prevention guidelines in the United States for heart disease, stroke, hypertension and diabetes focus heavily on medications and lifestyle behaviors,” said senior author Dr. Jian Li, an occupational epidemiologist and professor in the Fielding School’s departments of Environmental Health Sciences and Epidemiology. “Our results suggest that work conditions, including shift schedules, should also be part of the conversation between patients, clinicians, employers, and policy makers.”

The peer-reviewed study - “Long-term prognosis of cardiometabolic diseases among U.S. workers: The contribution of shift work to mortality” - has been published in the current edition of the American Journal of Preventive Cardiology; the authors include researchers from UCLA, Harvard University, the University of Colorado, and SUNY, as well as from Canada.

“This is among the first in the United States to examine how shift work affects long-term survival in people who are already living with conditions such as cardiovascular disease, hypertension, or diabetes,” said Xiang Li, a doctoral student in UCLA Fielding's Department of Epidemiology and first author of the study.

Analyzing data from a nationally representative sample of U.S. workers with cardiometabolic diseases, researchers found that shift work was associated with:

• 28% higher risk of death from any cause
• 57% higher risk of death related to cardiometabolic diseases
• 61% higher risk of death from cardiovascular disease

These associations persisted even after accounting for differences in age, sex, race and ethnicity, income, education, insurance status, and occupation, said Li, who also serves as a professor with UCLA’s Joe C. Wen School of Nursing.

Cardiometabolic diseases, including heart disease, stroke, hypertension, and diabetes, are among the leading causes of death in the United States. At the same time, roughly one fourth of American workers perform some form of shift work outside regular daytime hours.

“Many people with cardiovascular disease, hypertension, or diabetes continue working, often in jobs that require non-daytime schedules,” said co-author Dr. Paul Landsbergis, an associate professor in Department of Environmental and Occupational Health Sciences, SUNY Downstate Health Sciences University. “Yet workplace factors such as shift work are rarely considered in clinical guidelines for managing these conditions.”

The team analyzed data from the 2010 and 2015 National Health Interview Survey linked to mortality records through 2019. The study included 9,622 U.S. workers who reported having cardiometabolic diseases at baseline. About 26% reported working evening, night, or rotating shifts. During the follow-up period, 308 deaths in the non-shift work group and 129 deaths in the shift work group were documented.

“Relevant research findings of disrupted circadian rhythms, sleep loss, and physiological stress that associated with shift work may compound existing health risks.,” said co-author Dr. Imelda Wong, with the British Columbia Ministry of Health. “Social and economic factors, such as lower job control and reduced access to healthcare among shift workers, may also play a role.”

The findings point to work schedules as an important but underrecognized social determinant of health among workers, the researchers said.

“Most research on shift work focuses on whether it increases the chance of developing cardiovascular disease,” said co-author Dr. Tong Xia, a UCLA Fielding alum currently with the Harvard T.H. Chan School of Public Health, Brigham and Women's Hospital. “Our findings show that shift work may also worsen long-term outcomes for people who already have cardiometabolic conditions.”

Research support and funding

This research was supported by a 2024 Pilot Grant from the Joe C. Wen School of Nursing at the University of California, Los Angeles. Additional support was provided in part by the National Institute for Occupational Safety and Health through the Southern California Education and Research Center (SCERC).

The funders had no role in the design, analysis, interpretation, or publication of the study findings.