Scientists investigate why asthma gets worse at night

It has long been said that asthma often gets worse at night. Research teams at Brigham and Women's Hospital and Oregon Health & Science University have used two circadian protocols to clarify the importance of the role of the biological clock.

Study explores why asthma worsens at night

The research results were published in the bulletin of the National Academy of Sciences.

In the United States, 75% of 20 million asthma patients report that their symptoms worsen at night. Various factors such as exercise, temperature, posture, and sleeping environment are known to worsen the symptoms of asthma, but Dr. Frank AJL Shear, director of the Department of Sleep and Circadian Disorders at Brigam University, and Oregon Dr. Stephen A. Shea, director of the Institute of Occupational Health Sciences, investigated the impact of circadian rhythms on this issue.

The research team evaluated two experimental protocols to isolate the effects of circadian rhythm and other behavioral factors. In the 'constant routine' protocol, subjects were placed in a dimly lit environment, stayed awake for 38 consecutive hours in a constant position, and ate the same meal every two hours. The other 'forced async' protocol repeated a 28-hour sleep / wake cycle in a dim environment for a week, ensuring that all actions were performed evenly within the cycle.

The results showed that the 17 asthma patients who were the subjects used the inhaler four times more often at night in circadian rhythm than during the day.

'This study is one of the earliest studies to carefully isolate the effects of the circadian system from behavioral and environmental factors, including sleep,' commented Dr. Scheer.

'We found that people with the worst asthma symptoms had the greatest decrease in lung function at night caused by circadian rhythms, and that behaviors such as sleep also caused significant changes,' said Dr. Shea. increase.