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Nighttime (Nocturnal) Asthma

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:

  • 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.

For more information, see WebMD's article on Nocturnal Asthma.

Health Conditions That Mimic Asthma

Other health conditions can mimic asthma, which makes the correct diagnosis of asthma more difficult for your doctor.

For more information, see WebMD's article on Health Conditions That Mimic Asthma.


Cardiac Asthma

Cardiac asthma is one of the conditions that mimics asthma and usually occurs in elderly people who have wheezing and shortness of breath because of heart failure. When the heart is too weak to pump blood effectively, fluid will accumulate in the lungs and cause shortness of breath and wheezing. A chest X-ray can help diagnose heart failure by showing an enlarged heart (usually a sign of heart failure) along with fluid in the tissues of the lung. Treatment of heart failure involves using diuretics (water pills) to rid the lungs of excess fluid and medications to help the heart muscle pump more effectively. When heart failure is controlled, the wheezing will stop. Some people may suffer from asthma and heart failure simultaneously. These patients require treatment for both health conditions to improve their quality of life.

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