Circadian Rhythms and Nocturnal Asthma

Nocturnal worsening of asthma, frequently called NA, is a common problem among some people with asthma and one that leads to increased morbidity and mortality. It is still unknown why lung function worsens at night in some asthmatics and not others. There is a possible relationship between NA, biological clocks, and circadian rhythms, but more research is needed to understand this relationship. Although the diurnal nature of NA has been shown repeatedly in studies, circadian rhythms have not yet been implicated as a related factor. This study will examine the pathophysiology of NA as it relates to circadian biology and will specifically explore physiological and molecular aspects.

This study will include people with asthma, people with NA, and healthy people. Potential participants will attend a screening visit to assess general health and severity of asthma, if present. They will also complete 2 weeks of diary recordings of their daily symptoms and airway function.

Eligible participants will then attend two study visits. The first study visit will last 1 hour and may include a methacholine challenge and bronchodilator testing, both of which will measure lung function. For 2 weeks before the second study visit, participants will keep records of their sleep patterns. The second study visit will be a hospital stay that will last for 2.5 days. While in the hospital, participants will undergo periodic blood draws and lung function testing. During waking hours, participants will remain quietly awake. During the first night, participants will be monitored while they sleep. During the second night, participants will stay awake for 28 hours, which will continue into the third day. Then, on the third day, participants will sleep for 8 hours while again being monitored. Upon waking, participants will be given a regular meal and discharged.