DEPRESSION & MOOD DISTURBANCE. Regular (daily) T'ai Chi practitioners usually find less incidence of depression and overall mood disturbance.
Relative to measurement beforehand, practice of Tai Chi raised heart rate, increased nonadrenaline excretion in urine, and decreased salivary cortisol concentration. Relative to baseline levels, [Test Subjects] reported less tension, depression, anger, fatigue, confusion and state-anxiety; they felt more vigorous, and in general they had less total mood disturbance.
(American Psychological Association) Journal of Psychosomatic Research, 1989 Vol 33 (2) 197-206