
A new study has found that women who work night shifts are more likely to have moderate or severe asthma compared to women who work during the day. The study, published in ERJ Open Research, looked at data from over 2.7 lakh (270,000) people. It showed that this increased asthma risk was not seen in men. In men, the chances of having asthma were the same whether they worked during the day or at night.
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According to the study, women who only work at night are about 50% more likely to suffer from moderate or severe asthma than those who work only in the daytime.
Dr. Robert Maidstone from the University of Manchester, UK, said,
“Asthma affects women more than men. Women often have more serious asthma, and they are more likely to be hospitalised or even die because of it.”
He added,
“This is the first study to look at how night shifts affect asthma in men and women differently. We found that women working permanent night shifts had a higher chance of having serious asthma than women working during the day.”
The researchers studied 274,541 working people and found that 5.3% had asthma, and 1.9% had moderate or severe asthma (meaning they needed stronger treatments like inhalers and steroids).
While the exact reason isn’t clear, scientists believe it could be because working night shifts disturbs the body’s natural clock (also called the circadian rhythm), which may affect hormone levels in the body.
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Testosterone, a hormone found more in men, is thought to help protect against asthma. Since women naturally have lower testosterone levels, this might make them more at risk. Also, the types of jobs men and women do on night shifts might be different, which could also be a reason.
The study also found that postmenopausal women (who are no longer having periods) who worked night shifts had almost double the risk of moderate or severe asthma – especially those not taking hormone replacement therapy (HRT).
Dr. Maidstone said,
“It looks like HRT may help protect night-working women from asthma, but we need more studies to confirm this.”
The researchers now plan to study how sex hormones affect the link between shift work and asthma in more detail.