Nocturnal asthma, with symptoms like chest tightness, shortness of breath, cough, and wheezing at night, can make sleep impossible and leave you feeling tired and irritable during the day. These problems may affect your overall quality of life and make it more difficult to control your daytime asthma symptoms.
Nighttime Asthma and Sleep Disturbance
The chances of experiencing asthma symptoms are higher during sleep. Nocturnal wheezing, cough, and trouble breathing are common yet potentially dangerous. Many doctors often underestimate nocturnal asthma or nighttime asthma.
Studies show that most deaths related to asthma symptoms such as wheezing occur at night.
Nocturnal Asthma Causes
The exact reason that asthma is worse during sleep are not known, but there are explanations that include increased exposure to allergens; cooling of the airways; being in a reclining position; and hormone secretions that follow a circadian pattern. Sleep itself may even cause changes in bronchial function.
Increased Mucus or Sinusitis
During sleep, the airways tend to narrow, which may cause increased airflow resistance. This may trigger nighttime coughing, which can cause more tightening of the airways. Increased drainage from your sinuses can also trigger asthma in highly sensitive airways. Sinusitis with asthma is quite common.
Asthma problems may occur during sleep, despite when the sleep period is taking place. People with asthma who work on the night shift may have breathing attacks during the day when they are sleeping. Most research suggests that breathing tests are worse about four to six hours after you fall asleep. This suggests there may be some internal trigger for sleep-related asthma.
Lying in a reclining position may also predispose you to nighttime asthma problems. Many factors may cause this, such as accumulation of secretions in the airways (drainage from sinuses or postnasal drip), increased blood volume in the lungs, decreased lung volumes, and increased airway resistance.
Breathing colder air at night or sleeping in an air‑conditioned bedroom may also cause loss of heat from the airways. Airway cooling and moisture loss are important triggers of exercise‑induced asthma. They are also implicated in nighttime asthma.
If you are frequently bothered with heartburn, the reflux of stomach acid up through the esophagus to the larynx may stimulate a bronchial spasm. It's worse when lying down or if you take medications for asthma that relax the valve between the stomach and esophagus. Sometimes, acid from the stomach will irritate the lower esophagus and lead to constriction of your airways. If stomach acid backs up to your throat, it may drip down to the trachea, airways and lungs, leading to a severe reaction. This can involve airway irritation, increased mucus production, and airway tightening. Taking care of GERD and asthma with appropriate medications can often stop nighttime asthma.
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.