Three-point moving averages of the hourly VAS rating of irritability in women with PMDD who were treated with fluoxetine during the luteal phase, and women with PMDD who received no treatment. Ratings in women receiving fluoxetine represent pretreatment ratings (Day −2, −1) and after receiving fluoxetine 20 mg daily in morning on Day 1, whereas ratings in untreated women represent ratings premenses (Day −2, −1) and after the onset of menses (Day 1). The onset of menses and the initiation of SRI treatment were accompanied by similar patterns of symptom response (ANOVA-R of the ratings for all four symptoms during Day 1–3 demonstrated an identical pattern of symptom improvement with significant effects of both day and hour that reflected an improvement in scores of all four symptoms after the onset of either SRI treatment or menses (main effect of day F2,32 = 8.3, P = .003; main effect of hour F9,144 = 5.9, P < .001).