Night shift work linked to higher asthma risk in women

Night shift work linked to higher asthma risk in women | Image Credit: © bobex73 - © bobex73 - stock.adobe.com.

The odds of moderate or severe asthma are increased among women working night shifts vs during the daytime, according to a recent study published in ERJ Open Research.¹

Gender differences in asthma risk

This research was conducted after earlier data highlighted increased odds of moderate or severe asthma in night shift workers, in order to determine how this link varied between women and men. In this data from 270,000 individuals, men did not have an increased risk of asthma when working night shifts, with this link only reported in women.

“This type of research cannot explain why shift work and asthma are linked; however, it could be because shift work disrupts the body clock, including the levels of male and female sex hormones,” said Robert Maidstone, PhD, from the University of Manchester.

The trial included UK Biobank participants aged 40 to 69 years with paid employment or self-employed at baseline.² Self-reported doctor diagnosis and medication used were identified to determine moderate and severe asthma cases. This led to asthma being reported in 5.3% of the cohort and moderate or severe asthma in 1.9%.

Classification of shift work and chronotypes

Classifications of shift work included day worker, shift worker but only rarely at nights, irregular shift work including nights, and permanent night shifts. Participants also reported their category of chronotype, which included definitely a morning person, intermediate chronotype, and definitely a night person.

Sex differences were determined based on measurements of testosterone, sex hormone binding globulin, and oestradiol. The reference group included patients with oestradiol measurements below 175pmol/L.

Similar ages were observed between men and women, though women were less likely to smoke and drink alcohol than men. Similar trends across work schedule groups were also reported between these sexes. Women reported working fewer hours than men and coming from more deprived areas, especially when working night shifts.

Asthma Risk by work type in women vs men

Other categories of working were linked to an increased risk of moderate or severe asthma vs day work among women. Odds ratios (ORs) were 1.16 for shift workers rarely working night shifts, 1.18 for irregular shift workers including night, and 1.54 for permanent night shift workers.

For male patients, these ORs were 1.05, 0.94, and 0.91, respectively, highlighting no significant differences compared to day shift working men. Similar results were reported after adjustments for covariates, with an OR of 1.50 for moderate or severe asthma among permanent night shift women vs day shift women.

Conclusions and recommendations

These results indicated increased rates of moderate to severe asthma in women with shift or night work vs daytime work, but not in men. Investigators recommended intervention studies to evaluate how modifying work schedules may reduce asthma risk in women.

“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,” said Florence Schleich, PhD, from the European Respiratory Society.¹

References:

1. Women who work nightshifts are more likely to have asthma. European Respiratory Society. June 15, 2025. Accessed June 17, 2025. https://www.eurekalert.org/news-releases/1087074.
2. Maidstone RJ, Ray DW, Liu J, Bowden J, Rutter MK, Durrington HJ. Increased risk of asthma in female night shift workers. ERJ Open Research. 2025.doi:10.1183/23120541.00137-2025