Nocturnal Asthma: A Special Type of Asthma

Nocturnal asthma is defined by a drop in forced expiratory volume in 1 second (FEV1) of at least 15% between bedtime and awakening in patients with clinical and physiologic evidence of asthma. Nocturnal asthma is associated with a circadian pattern in lung function, distal airway inflammation, glucocorticoid receptor affinity, pulmonary capillary blood volume, and beta-2 adrenergic receptor function may also contribute.