Nocturnal events related to "morning dipping" in bronchial asthma.

The mechanism of early morning bronchospasm in asthma was investigated by analyzing circadian variations in the plasma levels of cortisol, ACTH, epinephrine, and norepinephrine, as well as in the serum neutrophil chemotactic activity and heart rate in asthmatic patients with (n = 6) and without (n = 7) "morning dipping" and normal subjects. Findings suggested that an exaggerated nocturnal nadir in plasma cortisol levels may precipitate "morning dipping" in some patients with asthma.