Middle-aged and older adults with a history of shift work are at increased risk of developing frailty, compared to those working daytime hours only, suggests a study in the May Journal of Occupational and Environmental Medicine.
Led by Durdana Khan, MSc, of York University, Toronto, Ont., Canada, the researchers analyzed the relationship between shift work and subsequent frailty in a nationally representative sample 47,740 employed adults in Canada. A little over half of participants were women; average age at first evaluation was about 60 years.
Overall, 21% of participants reported doing shift work at some time during their careers. At 3 years' follow-up, 7.2% had developed frailty, based on a standard Frailty Index. Frailty risk tended to be higher among participants reporting shift work—although most associations were not statistically significant after adjustment for other factors.
However, women who had ever been exposed to shift work were significantly more likely to develop frailty over 3 years. Risk was 41% higher than for women reporting daytime work only.
Risk was even greater for women who reported rotating shift work in their longest-lasting job: 55% higher than for women with no shift work. Participants reporting shift work in their current job were not at increased risk, possibly reflecting a "healthy worker" effect.
Frailty is a common medical syndrome in older adults, with characteristics including decreased strength, endurance, and physiological functioning. Frail individuals are at increased risk of premature death, institutionalization, and worsening disability.
Previous studies have reported negative effects of shift work on employee well-being—possibly resulting from factors such as misalignment of normal circadian (sleep-wake) cycles and sleep disruption. The new study is the first to investigate the associations between shift work exposure and frailty.
The results provide new evidence linking a history of shift work to an increased risk of frailty in older workers with a history of shift work are at higher risk of frailty. The association is independent of other characteristics in women, and particularly those reporting rotating shift work.
"Although these findings are preliminary, they suggest that circadian disruption may be an important factor" in the development of frailty in working adults, Ms. Khan and colleagues conclude. "[T]he role of shift work exposure in the risk of frailty warrants further investigation."
About the Author
Ms. Khan may be contacted for interviews at firstname.lastname@example.org
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About the Journal of Occupational and Environmental Medicine
The Journal of Occupational and Environmental Medicine (www.joem.org
) is the official journal of the American College of Occupational and Environmental Medicine. Edited to serve as a guide for physicians, nurses, and researchers, the clinically oriented research articles are an excellent source for new ideas, concepts, techniques, and procedures that can be readily applied in the industrial or commercial employment setting.