Premenstrual dysphoric disorder (PMDD) is characterized by a cyclical symptom course. Previous research provides limited findings on possible menstrual-cycle-related psychological and psychoendocrinological processes in PMDD. By using ambulatory assessment (AA), we aimed to compare mood and cortisol cyclicity in individuals with PMDD and healthy controls (HC), and to assess effects of habitual and momentary repetitive negative thinking (RNT) and present moment awareness (PMA) on mood …