MULTICOMPONENT PHYSIOLOGICAL-RESPONSE MEDIATES THERAPEUTIC BENEFITS OF BRIGHT LIGHT IN WINTER SEASONAL AFFECTIVE-DISORDER

The set of investigations was designed to determine whether bright lig ht improves both psychic and physiological functions in patients with winter seasonal affective disorder. The signs of such physiological ef fects of light as advance of circadian phase, increase in energy expen diture and activation of sympatho-adrenal system were examined in 61 f emale patients with winter depression and 36 age matched controls befo re and after 1-week treatment (2,500 lux of white light for 2 h daily) . Moreover, the indicators of the fourth physiological effect, intensi fication of non-rapid eye movement sleep, were studied in a subsample of 21 patients and 10 controls. Although the results provide little ev idence for a strong association between different physiological respon ses to light, any of four responses appears to be positively associate d with a remission of the depressive syndrome. The findings indicate t hat neither of physiological responses could play a dominant role, but several additive effects (e.g. responses of sleep-regulating, circadi an, energy-regulating and sympatho-adrenal systems) could be necessary for the favorable therapeutic response to bright light. This result r aises the possibility that physiology really participates in regulatin g the mood of winter depressives. However, any simple pathophysiologic al model of SAD seems not to be adequate.