Nighttime (nocturnal) asthma is a very common type of asthma, with more than 90% of asthma patients experiencing nighttime wheezing and coughing. Symptoms of asthma are most common between midnight and 8 a.m. and can cause insomnia and sleep deprivation among people with asthma. In fact, sleep disturbances in people with asthma usually mean that their asthma is inadequately controlled and warrants a visit to the doctor to re-evaluate the prescribed asthma medications.
Lung function in a person with asthma can decline by up to 50% during an episode of nocturnal asthma. The reasons are not clear, but possible explanations include:
It is possible to test for nocturnal asthma by taking measurements of airflow out of the lungs while exhaling (peak flow) in the evening and again upon awakening in the morning. This is done with an asthma test called a peak flow meter -- a small, portable meter that measures the flow of air. (An asthma specialist can demonstrate the correct technique for making these measurements.) A greater than 20% decrease in the peak flow measurement from the evening to the morning suggests nocturnal asthma.
Lung function in a person with asthma can decline by up to 50% during an episode of nocturnal asthma. The reasons are not clear, but possible explanations include:
- Exposure to allergens at night such as dust mites or animal dander.
- Changes in the levels of hormones such as cortisol, histamine, and epinephrine at night, resulting in increased reactivity of the airways.
- Longer periods of exposure to asthma triggers within the bedroom.
- Reflux of stomach acid into the esophagus (GERD) related to laying down (heartburn and asthma)
- A late reaction to daytime asthma triggers.
- Cooling of the airways that cause spasm of the major airways.
- Sinusitis and postnasal drip.
- Sleep apnea.
It is possible to test for nocturnal asthma by taking measurements of airflow out of the lungs while exhaling (peak flow) in the evening and again upon awakening in the morning. This is done with an asthma test called a peak flow meter -- a small, portable meter that measures the flow of air. (An asthma specialist can demonstrate the correct technique for making these measurements.) A greater than 20% decrease in the peak flow measurement from the evening to the morning suggests nocturnal asthma.
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