Nocturnal Asthma (Nighttime Asthma)
Nocturnal Asthma Causes continued...
Late Phase Response
If you are exposed to an allergen or asthma trigger, the chances are great that airway obstruction or allergic asthma will occur shortly afterward. This acute asthma attack ends within one hour. About 50% of those who experience an immediate reaction also have a second phase of airway obstruction within three to eight hours of exposure to the allergen. This phase is called the late phase response, and it is characterized by an increase in airway responsiveness, development of bronchial inflammation, and a more prolonged period of airway obstruction.
Many studies report that when allergen exposure occurs in the evening instead of in the morning, you are more susceptible to having a late phase response and are more likely to have one of greater severity.
Hormones that circulate in the blood have well‑characterized circadian rhythms that are seen in everybody. Epinephrine is one such hormone, which exerts important influences on the bronchial tubes. This hormone helps keep the muscle in the walls of bronchi relaxed so the airway remains wide. Epinephrine also suppresses the release of other substances, such as histamines, which cause mucus secretion and bronchospasm. Your epinephrine levels and peak expiratory flow rates are lowest at about 4:00 a.m., while histamine levels tend to peak at this same time. This decrease in epinephrine levels may predispose you to nocturnal asthma during sleep.
How Is Nocturnal Asthma Treated?
There is no cure for nighttime asthma, but daily asthma medications, such as inhaled steroids, are very effective at reducing inflammation and preventing nocturnal symptoms. Since nocturnal asthma or nighttime asthma may occur anytime during the sleep period, asthma treatment must be sufficient to cover these hours. A long-acting bronchodilator delivered in an asthma inhaler can be effective in preventing bronchospasm and symptoms of asthma. If you suffer from nocturnal asthma, you may also benefit from a long-acting inhaled corticosteroid. If you suffer with GERD and asthma, ask your doctor about medication that reduces acid production in the stomach. Avoidance of potential allergy triggers such as dust mites, animal dander, or feathers in a down comforter may also be very helpful in preventing allergies and asthma and nocturnal asthma attacks.
In addition, using your peak flow meter, you can monitor how your lung function is altered throughout the day and night. Once you notice this altered pattern of lung function, talk with your doctor about a plan to resolve your nighttime asthma symptoms. According to your type of asthma and asthma severity (mild, moderate, or severe), your doctor can prescribe treatment to help you resolve your nighttime asthma symptoms so you can sleep like a baby.