Patterns in affect and personality states across the menstrual cycle.

Affective, behavioral, and cognitive (i.e., personality) states fluctuate across situations and context, yet the biological mechanisms regulating them remain unclear. Here, we report two large, longitudinal studies that investigate patterns of change in personality states and affect as a function of the menstrual cycle, ovarian hormones, and hormonal contraceptive use. Study 1 (N = 757) is an online diary study with a worldwide sample, whereas Study 2 (N = 257) is a laboratory study including repeated hormone assays. Both studies came to somewhat diverging conclusions. In Study 1, we found that dynamics of daily affect and personality were very similar among naturally cycling women and hormonal contraceptive users, with two exceptions: Hormonal contraceptive users showed greater variability in negative affect than naturally cycling women, and, naturally cycling women showed a descriptive, but nonsignificant decrease in positive affect in the premenstrual phase. Results of Study 2 indicated robust premenstrual increases in neuroticism and negative affect but decreases in extraversion and positive affect. High extraversion and low neuroticism were positively related to conception risk and the estradiol-to-progesterone ratio, suggesting potentially adaptive effects consistent with a fertility-induced shift in motivational priorities. We discuss how differences in methods likely account for differences in results between both studies and suggest methodological and theoretical guidelines for future research. Taken together, our results suggest that hormonal variation across the menstrual cycle-and discrete menstrual cycle events, such as premenstruation-represent potential biological sources of personality state variation. (PsycInfo Database Record (c) 2025 APA, all rights reserved).