Asthma and Circadian Rhythm

26 Oct Asthma and Circadian Rhythm

New research has investigated the link between asthma and our bodies circadian rhythm. The circadian system is critical for the coordination of bodily functions and to anticipate the daily cycling environmental and behavioural demands.

Many people who suffer asthma often report worsening of symptoms during the night, and while many behavioural and environmental factors (exercise, air temperature, posture, and sleep environment) are known to influence asthma severity, researchers wanted to explore how much our bodies internal clock contributes to this.

Study participants were separated into two groups where complementary laboratory protocols were used to continuously assess lung function, asthma symptoms and bronchodilator use. One group spent 38hrs awake under a controlled protocol, while the other group were placed on a recurring 28-hour sleep/wake cycle for a week.

The researchers observed that those people who have the worst asthma in general are the ones who suffer from the greatest circadian-induced drops in pulmonary function at night, and also had the greatest changes induced by behaviours, including sleep. They also found that these results are clinically important because, when studied in the laboratory, symptom-driven bronchodilator inhaler use was as much as four times more often during the circadian night than during the day.


Story Source:

Brigham and Women’s Hospital. “Study explores why asthma worsens at night.” ScienceDaily. ScienceDaily, 6 September 2021. <>


Journal Reference:

Frank A. J. L. Scheer, Michael F. Hilton, Heather L. Evoniuk, Sally A. Shiels, Atul Malhotra, Rena Sugarbaker, R. Timothy Ayers, Elliot Israel, Anthony F. Massaro, Steven A. Shea. The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles. Proceedings of the National Academy of Sciences, 2021; 118 (37): e2018486118 DOI: 10.1073/pnas.2018486118