New research suggests that women who work night shifts are more likely to suffer from moderate to severe asthma than those who work only during the day. This increased risk was not seen in men, according to the study published in ERJ Open Research. The study was conducted by Dr. Robert Maidstone and his team from the University of Manchester, UK. They analyzed data from more than 270,000 working people in the UK, making it one of the largest studies to explore this link.
Asthma affects women more seriously
“Asthma disproportionately affects women,” said Dr. Maidstone. “Women generally experience more severe asthma, are hospitalized more often, and even have a higher death rate from asthma compared to men.”
He added that in their previous research, they found that night shift workers had a higher risk of asthma. This time, they wanted to dig deeper and explore the differences between men and women.
What the study found
The researchers used information from the UK Biobank, a large database of health records. Out of 274,541 working professionals, around 5.3 per cent had asthma, and 1.9 per cent had moderate to severe asthma—meaning they used both a preventer inhaler and other treatments like steroids.
The participants were grouped based on their work schedules: those who worked only during the day, those who only worked night shifts, and those with rotating shifts.
Here’s what they found:
- Women who only worked night shifts were around 50% more likely to have moderate to severe asthma compared to women who worked only during the day.
- Shift-working women in general had a higher risk of asthma.
- In men, asthma risk remained the same regardless of whether they worked during the day or night.
Why is there a difference?
Dr. Maidstone explained that this is the first study to look at how shift work affects asthma differently in men and women.
Although the study doesn’t prove the exact cause, researchers believe that disruption to the body’s natural clock (circadian rhythm) due to night shifts could be a factor. Hormones may also play a role.
“High testosterone levels have been shown to protect against asthma,” Dr. Maidstone said. “Since women naturally have lower testosterone, this might make them more vulnerable. Also, men and women might be doing different types of shift jobs, which could contribute.”
Postmenopausal women at higher risk
In postmenopausal women, the risk of asthma was nearly double for those working night shifts compared to those working during the day—especially in women who were not taking hormone replacement therapy (HRT).
This finding has led researchers to wonder whether HRT might offer some protection against asthma in night shift workers, though more studies are needed to confirm this.
The research team now plans to explore the role of sex hormones and shift work in more detail. They will use more data from the UK Biobank and another program called Our Future Health.
Professor Florence Schleich, a lung expert from the University of Liege in Belgium, was not involved in the study but agrees the findings are important.
“Asthma is a serious and long-term illness that affects millions globally. Women tend to have more severe symptoms, but we don’t fully understand why,” she said. “This study suggests that night shift work could be a risk factor, but we need more research.”
She added, “Most people don’t have the luxury of changing their work hours easily. So, it’s important to find ways to reduce the health risks for shift-working women.”
If you’re a woman working night shifts and facing ongoing breathing issues, it’s important to consult a doctor. As research continues, awareness and early diagnosis remain key to managing asthma and protecting long-term health.
