Night Shift Associated With Asthma Risk In Women

WEDNESDAY, June 18, 2025 (HealthDay News) — Women working the night shift appear to have an increased risk of asthma, a new study says.

Women who only work nights have a 50% increased risk of moderate to severe asthma compared to those on the day shift, researchers reported June 16 in the journal ERJ Open Research.

Researchers did not find a similar link between night shift work and asthma in men.

“This type of research cannot explain why shift work and asthma are linked,” lead researcher Robert Maidstone, a research fellow at the University of Manchester in the U.K., said in a news release. “However, it could be because shift work disrupts the body clock, including the levels of male and female sex hormones.”

Bolstering this argument, researchers found that postmenopausal women on the night shift not using hormone replacement therapy had a nearly doubled risk of moderate to severe asthma, results show.

Asthma is already known to disproportionately impact women more than men, researchers said in background notes.

“Women generally have more severe asthma, and higher rate of hospitalization and death from asthma compared to men,” Maidstone said.

Previous research also has found that night shift workers are more likely to have moderate or severe asthma.

This led researchers to see if night shift work would drive asthma risk even higher among women.

For the study, researchers tracked the health of nearly 275,000 working people participating in the U.K. Biobank, a large-scale health research project in the United Kingdom.

More than 5% of those workers had asthma, including 2% suffering from severe asthma that required a rescue inhaler.

Results showed that women who only work on the night shift had 50% higher odds of moderate to severe asthma.

What’s more, risk was 89% higher among women on the nightshift who were past menopause and not taking hormone replacement therapy.

“Our results suggest that HRT might be protective against asthma for nightshift workers,” Maidstone said. “However, further research is needed to test this hypothesis in prospective studies and randomized controlled trials.”

Men might be protected against asthma due to their high testosterone levels, he said.

“High testosterone has previously been shown to be protective against asthma, and so lower testosterone in women could play a role,” Maidstone noted.

However, because this study can’t draw a direct cause-and-effect link, some other factor might also contribute to women’s increased risk, Maidstone said. For example, the different types of shift jobs held by men and women could play a role in asthma risk.

It will be difficult for workers to use this knowledge directly to protect their lung health, noted Florence Schleich, a European Respiratory Society expert on asthma.

“The majority of workers will not have an easy option of switching their shift pattern, so we need further research to verify and understand this link and find out what could be done to reduce the risk for women who work shifts,” Schleigh, an associate professor atthe University of Liege in Belguim, said in a news release. She was not involved in the research.

More information

Asthma + Lung UK has more asthma and women on.

SOURCE: European Respiratory Society, news release, June 16, 2025