Night Shifts May Increase Asthma Risk in Women: Study

New Delhi – Women working night shifts may face a significantly higher risk of developing moderate to severe asthma compared to their daytime counterparts, according to a large-scale study involving over 270,000 participants.

Published in ERJ Open Research, the study found that women who exclusively worked night shifts were about 50% more likely to suffer from moderate or severe asthma than those who only worked during the day. Interestingly, no such link was found in men—regardless of whether they worked night or day shifts, their risk of asthma remained largely unaffected.

"Asthma disproportionately affects women. They generally experience more severe symptoms and face higher rates of hospitalisation and asthma-related deaths than men,” said Dr. Robert Maidstone from the University of Manchester, UK. “This is the first study to explore gender differences in the relationship between shift work and asthma. We observed that permanent nightshift work is associated with a higher risk of moderate to severe asthma in women.”

The research builds on earlier findings that nightshift work may be linked to worsening asthma, and it delves deeper by evaluating gender-based differences. The study analyzed data from 274,541 working individuals, out of which 5.3% had asthma and 1.9% suffered from its moderate or severe form—defined as needing a preventative inhaler and at least one additional treatment such as oral steroids.

Although the exact reason behind the association remains unclear, researchers suspect that nightshift work disrupts the body’s natural circadian rhythm, potentially altering levels of sex hormones. Lower testosterone levels—typically found in women—may offer less protection against asthma. The type of jobs typically held by men versus women during night shifts could also play a role.

For postmenopausal women not on hormone replacement therapy (HRT), the risk of moderate to severe asthma was nearly twice as high in night workers compared to day workers. This raises the possibility that HRT may offer some protective effect—a theory researchers aim to investigate further through future studies and clinical trials.

“Our findings indicate a potential protective role of hormone replacement therapy for nightshift workers, but more research is needed to confirm this in larger, controlled studies,” said Dr. Maidstone.

The research team’s next steps involve studying the role of sex hormones in the link between shift work and asthma.

With inputs from IANS