Nocturnal asthma is a term used to describe the asthma of patients whose symptoms strike mostly at night – often while the patient is sleeping. The majority of these asthma attacks occur between midnight and 8 a.m., peaking on average around 4 a.m. Nearly 75 percent of asthma patients experience increased symptoms at night, according to the American Academy of Allergy, Asthma and Immunology.

People with asthma experience inflammation of the bronchial tubes, even when symptoms are not present. This causes a narrowing of the airways and an increased sensitivity to allergens or other stimuli. Exposure to these triggers often produces symptoms such as coughing, wheezing and an inability to breathe normally (shortness of breath). In rare cases, a severe asthma attack can be fatal.

For reasons not completely understood, asthma symptoms tend to occur far more often at night. One British study found that the majority of asthma–induced hospital deaths and episodes of ventilatory arrest occur at night. Regular nocturnal asthma episodes are often an indicator of a severe asthma condition or one which needs additional treatment. However, experts are unsure whether nocturnal asthma is its own unique condition or just a symptom of severe asthma.

Individuals who experience nocturnal asthma symptoms should report them to their physician. Medication changes can often be made to better treat this type of condition.

The breathing problems associated with nocturnal asthma often cause patients to awaken during the night. Disruptions in the amount or quality of sleep can result in daytime sleepiness, and affect the ability to learn and perform tasks. Therefore, treatment for nocturnal asthma can also improve quality of life.

Signs and symptoms of nocturnal asthma are the same as with other asthmatic conditions, though they are often underreported to physicians because they occur at night.