Daijiworld Media Network - New York

New York, Jun 16: Women working night shifts face a significantly higher risk of developing moderate to severe asthma compared to their daytime counterparts, according to a major new study involving over 270,000 participants. The research, published in ERJ Open Research, found no such elevated risk in men working similar hours.

The study revealed that women working exclusively night shifts were about 50% more likely to suffer from moderate or severe asthma than those working regular daytime schedules. In contrast, asthma risk among men remained consistent regardless of their work shifts.

"Asthma tends to impact women more severely than men, with higher rates of hospitalisation and mortality,” explained Dr. Robert Maidstone of the University of Manchester, UK, who led the research. “This is the first large-scale study to examine how shift work may influence asthma risk differently based on sex. We discovered that permanent night shift work was associated with a notably higher likelihood of moderate to severe asthma in women.”

The study analyzed health data from 274,541 working adults. Among them, 5.3% were diagnosed with asthma, and 1.9% suffered from more serious forms of the condition—requiring both preventive inhalers and additional treatments such as oral steroids.

Although the precise reasons for the increased asthma risk remain unclear, the researchers suggest that the disruption of circadian rhythms caused by shift work could interfere with hormone levels, particularly sex hormones. Testosterone, for example, has been shown to offer some protection against asthma—meaning lower levels in women might be a contributing factor.

Another theory is that men and women may be concentrated in different types of night shift jobs, potentially exposing them to different environmental or occupational risks.

The study also found that postmenopausal women not undergoing hormone replacement therapy (HRT) and working night shifts had nearly double the risk of moderate to severe asthma compared to day workers. This led researchers to hypothesize that HRT may offer some protective benefits against asthma in such cases.

“We believe that hormone therapy might play a role in reducing asthma risk for night shift workers,” Dr. Maidstone noted. “However, more targeted studies and clinical trials are needed to confirm this.”

The team now plans to explore in greater detail how sex hormones interact with shift work to influence respiratory health outcomes.