Nocturnal asthma is a common and troublesome problem. Many possible mechanisms have
been proposed, including exposure to allergens, sleep itself, the supine posture, withdrawal
of bronchodilator drugs, gastric reflux, mucus plugging, and airway cooling. Although these
may be contributory factors in individual patients, they cannot provide a universal
explanation for the phenomenon of nocturnal and early morning wheezing. It now seems
that nocturnal asthma may best be understood in terms of circadian rhythms. A circadian …