Study links night shift work to increased risk of asthma

Manchester, England — Shift workers, particularly those working permanent night shifts, may be at elevated risk for moderate to severe asthma, according to a study led by British researchers.

The researchers looked at data for more than 280,000 UK Biobank participants and made adjustments for “major confounding factors” such as smoking history, ethnicity, socioeconomic status, physical activity and body mass index.

Results show that permanent night shift workers had a 36% greater chance of having moderate to severe asthma than employees who worked “normal office hours.” The odds of developing moderate to severe asthma were 55% higher for those working irregular shifts, including nights, than workers who consistently had the same shift.

Around 20% of employees in the industrialized world work permanent or rotating night shifts, the researchers note. Shift work can cause a person’s body clock, or circadian rhythms, to be out of tune with the outdoor light and darkness. This can lead to increased risks of cardiovascular disease, cancer and various metabolic disorders, according to a BMJ Publishing Group press release.

“The public health implications of these findings are far-reaching due to the high prevalence and co-occurrence of both asthma and shift work,” the researchers concluded.

They note that follow-up studies are needed. Those might include determining the effectiveness of a modified work schedule based on a person’s “chronotype” – their body clock preference for morning or evening activity. The researchers add that that might prove “a public health measure to reduce the risk of developing inflammatory diseases such as asthma.”

The study was published online Dec. 15 in the journal Thorax.