Psychologically induced airways changes in asthmatic individuals may be a function of variation in general activation level, not variation in asthma severity. The evidence for this hypothesis derives from work showing that healthy individuals exhibit psychologically induced airways changes similar to those exhibited by asthmatics. Individuals from both normal and healthy populations display increases in bronchomotor tone in response to stress and decreases in bronchomotor tone in response to relaxing stimulation. Although these responses are not limited to asthmatics, they are not irrelevant to asthma. Knowledge of specific relationships between airways changes and psychological factors is helpful in the management of asthma.