IS DIURNAL-VARIATION OF MOOD ASSOCIATED WITH PARASYMPATHETIC ACTIVITY

18 patients with distinct improvement of mood in the evening and 18 pa tients without, both suffering from major depression and equally treat ed with tricyclic antidepressants (TCA), and an age- and sex-matched g roup of 18 normal control subjects underwent a standardized heart-rate (HR) analysis (HRA) in the morning (08:00) and 12 h later in the even ing (20:00). The battery of cardiovascular reflex tests included the d etermination of HR variability (HRV) while resting and during deep bre athing, and a spectral HRA. The depressed patients with diurnal variat ion of mood showed significantly decreased HR and significantly increa sed HRV parameters while resting and during deep respiration in the ev ening. On the contrary, patients without diurnal changes of mood just showed a significant HRV increase during deep respiration in the eveni ng. No statistically significant changes of these parameters were dete cted in the healthy subjects. It is not known if the observed changes of HR parameters representing increment of parasympathetic tone are in trinsically related to the mood swings or if this rhythm just becomes visible under the circumstances of depression. Also, the impact of TCA treatment upon the results remains to be elucidated.