Treatment of a patient with seasonal premenstrual syndrome

The authors identified a patient who had premenstrual syndrome (late luteal phase dysphoric disorder) only in the fall and winter and was virtually asymptomatic during the spring and summer. On the basis of previous experience with seasonal affective disorder, they treated the patient with bright artificial light, which reversed her symptoms. On subsequent occasions they reversed this treatment effect with oral melatonin administration and found that propranolol and atenolol, beta- antagonists that inhibit the production of melatonin, had a therapeutic effect similar to that of light. They discuss the implications of these findings in relation to the importance of melatonin as a mediator of seasonal rhythms in biology.