Shift work may delay menopause for some women, study shows

Toronto — Researchers at York University say they’ve found a link between women who perform shift work and delayed onset of natural menopause.

Using data from nearly 3,700 premenopausal women enrolled in the Canadian Longitudinal Study on Aging, the researchers found “a significant relationship” between women who work rotating shifts and delayed menopause. One potential reason is the tendency of shift work to disrupt a person’s body clock, or circadian rhythms, putting it out of sync with outdoor darkness and light cycles. A press release from the North American Menopause Society notes that extended exposure to artificial light during nighttime hours may suppress melatonin levels and trigger a disturbance of ovarian activity.

According to the National Institute on Aging, the menopausal transition for most women typically begins between ages 45 and 55. However, “age at natural menopause is a matter of concern for middle-aged and older women, because both early [and] late menopause may be a significant marker for subsequent morbidity and mortality,” the release states.

“This study shows a potential influence of circadian regulation on age at natural menopause, with current rotating shift work linked to later age at menopause and current night shift work linked to earlier age at menopause,” NAMS Medical Director Stephanie Faubion added. “Whether these differences in age at menopause are directly related to the effect of circadian rhythm changes on underlying hypothalamic regulation or are because of other sociodemographic factors such as chronic stress, economic insecurity, and substance use or abuse requires further study.”

The study was published online in the NAMS journal Menopause.