Discounting for Money, Food, and Sex, over the Menstrual Cycle

Abstract

Sexual desire, physical activity, economic choices and other behaviours fluctuate over the menstrual cycle. However, we have an incomplete understanding of how preferences for smaller sooner or larger later rewards (known as delay discounting) change over the menstrual cycle. In this pre-registered, cross-sectional study, Bayesian linear and quadratic binomial regression analyses provide compelling evidence that delay discounting does change over the menstrual cycle. Data from 203 naturally cycling women show increased discounting (preference for more immediate rewards) mid-cycle, which is at least partially driven by changes in fertility. This study provides evidence for a robust and broad-spectrum increase in delay discounting (Cohen’s h ranging from 0.1 to 0.4) around the fertile point in the menstrual cycle across multiple commodities (money, food, and sex). We also show, for the first time, that discounting changes over the menstrual cycle in a pseudo-control group of 99 women on hormonal contraception. Interestingly, such women increase their discounting of sex toward the end of the menstrual phase — possibly reflecting a prioritisation of bonding-related sexual activity before menstrual onset.

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“…Testosterone levels peak on the day Women have less sexual desire and lower testosterone levels after ovulation. After ovulation, progesterone levels rise, making orgasm difficult [12,13]. A woman's testosterone level remains constant in the latter days of her menstrual cycle, but her uterine lining increases, activating nerve endings and making her stimulated.…”

“…Menopause lowers estrogen levels, which inhibits sexual interest and causes vaginal dryness. Testosterone levels rise during menopause, which may increase desire [2,13,14].…”