THE MOLECULAR-BASIS FOR WINTER DEPRESSION

A pulse of light is capable of inducing the circadian phase-dependent gene expression in neurons. The phase or amplitude of the circadian rh ythms can be modulated by critically timed exposures to light. A signi ficant heritability for the light-induced responses has been observed in hamsters. In humans, light has been used for treatment of the light -dependent winter depressive disorder. A genetic predisposition for hi gh responsiveness to light may occur in patients with winter depressio n. The altered gene expression induced by light may account for a uniq ue sensitivity to light and mediate the anti-depressant effect of ligh t treatment.