DOES BRIGHT-LIGHT THERAPY INFLUENCE AUTONOMIC HEART-RATE PARAMETERS

30 inpatients suffering from major depression (DSM-III-R), who did not fulfill the criteria of seasonal affective disorder (SAD), were treat ed with either doxepin or amitriptyline as monotherapy and supportivel y with bright light for 14 days. From days 15 to 19, bright light was replaced by dim light. 18 drug-free control subjects underwent an anal ogous sequence of bright- and dim-light applications. Phototherapy was applied between 06:00 and 07:30. Heart-rate (HR) analysis was perform ed in the patients and control subjects before and after the 5th sessi on of bright and dim lights, respectively. 12 patients (40%) experienc ed improvement of mood during bright-light therapy (group I) while 18 (60%) did not (group II). Patients of group I, who reached significant ly higher scores in the seasonal pattern assesssment questionnaire tha n patients of group II, showed an increase of the coefficient of HR va riation (HRV) during deep breathing as well as an increment of the hig h-frequency (HF) peak of spectral analysis exclusively after the brigh t-light sessions. Patients of group II did not show a significant alte ration of these parameters, neither under the conditions of bright-lig ht treatment nor under dim light. The control subjects experienced an increment of the HF power exclusively after bright light. The results suggest that a distinct subgroup of patients with non-SAD major depres sion shows a more pronounced light-associated increment of parasympath etically controlled cardiac functions than the other depressed patient s and the controls. HRV measurements seem to be a valuable tool for fu rther psychophysiological studies on treatment response (e.g., to phot otherapy).