We studied the effect of constant illumination for 1 month on female GC (genetic catalepsy) and Wistar rats (control). Light exposure decreased the degree of cataleptic freezing in female GC rats (compared to the control). Norepinephrine concentration in cataleptic rats returned to normal under these conditions: this parameter increased in the corpus striatum and adrenal glands and decreased in the hypothalamus to a control level observed in intact Wistar rats.