Diurnal rhythm of asthma.

A diurnal rhythm in the occurrence and severity of asthma symptoms is almost universal with disturbed sleep due to enhanced symptoms at night paralleled by a change in lung function. The mechanisms involved are not completely understood. However, it appears to be related to an exaggerated response to a circadian rhythm in lung function observed in healthy individuals. The circadian nature of asthma must be considered in diagnosis and evaluating the adequacy of therapy. Inhaled therapy with additional suppressive and anti-inflammatory treatment as required should be effective in treating most patients with nocturnal asthma.