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 attacks occur between midnight and 8 a.m., peaking on average around 4 a.m. This is when pulmonary (lung) functions are at their lowest level, because circulating blood levels of epinephrine and cortisol – which protect the body against asthma – are at their lowest levels.

Nearly 75 percent of asthma patients experience increased symptoms at night, according to the American Academy of Allergy, Asthma and Immunology. Frequent bouts of nocturnal asthma may indicate that a patient’s asthma is not being properly controlled.

Experts believe several factors may be responsible for the increased incidence of asthma symptoms at night. These include the body’s circadian rhythms, the internal clock that regulates the ebb and flow of various chemicals and body functions.

Patients with nocturnal asthma should consult a physician. This condition is often an indicator of severe asthma or asthma that requires further treatment. Certain behavioral modifications can reduce the likelihood of night–time symptoms. Medications also are available in time-release or long-lasting formulations to ensure that a patient with nocturnal asthma gets the medicine they need when they need it most.