Nighttime can be an extremely difficult period for individuals with bronchial asthma. All asthma patients have more sensitive airways at night. Those with increased attacks at night, "nocturnal asthma," have been found to experience an eight fold increase in airway hyperreactivity.
Remember, the presence of nocturnal attacks is one of the factors that differentiates mild from moderate and severe asthmatics. Adding to the significance of nocturnal asthma is increasing data that fatal attacks are more common at night. Several studies show a greater incidence of severe and fatal attacks between midnight and eight A.M. This data has prompted greater investigation into the source and treatment of nocturnal asthma. What Causes Nocturnal Asthma? At one time it was thought nocturnal asthma was caused by the "wearing off" of medication during the night. Further research has shown that many factors are involved. Adrenal Connection It is well documented that there is a natural rhythm of the body in which many organs function differently during the night. The adrenal gland is no exception. During sleep the adrenal gland manufactures less cortisone and epinephrine, causing a drop in their blood levels. Both of these substances are protective against asthma to a certain extent and the dip in blood levels may be one explanation for nocturnal asthma attacks. Consider the Environment Patients suffering nocturnal asthmatic attacks should look carefully at their bedrooms for sources of irritation. Potential allergens commonly found in bedrooms include feather pillows, animal dander, and dust mites. Simply using pillow and mattress covers may dramatically reduce nocturnal attacks. Reflux Connection The relationship between asthma and the stomach was discussed. Some doctors believe some nocturnal asthmatic attacks may be caused by reflux of stomach acid into the esophagus and throat where it may be aspirated into the bronchial tubes. Aggressive treatment of gastroesophageal reflux may reduce the frequency of nocturnal attacks. Sinusitis and Nocturnal Asthma Animal studies suggest that aspirating infected material from the sinuses into the lower throat and bronchial tubes may produce nocturnal asthma attacks. Although this effect has yet to be proven in patients with asthma, the strong possibility of a connection should reinforce vigorous treatment of sinusitis. Other Factors in Nocturnal Asthma Additional factors may also play a role in nocturnal asthma. It appears there is some cooling of airways at night. In asthmatics this change in temperature may be enough to produce asthma attacks. This mechanism also plays a role in exercise induced asthma. Some element in the nervous system may also be more active at night. The vagus nerve in the cholinergic nervous system is more active at night, and an increase in vagal tone may constrict the bronchial airways. In asthma patients that may increase the frequency of attacks.