Effects of menstrual cycle phase on interoception: A daily experience sampling study across two cycles

Abstract Interoception – the processing of internal bodily signals – has been related to numerous aspects of mental and physical health. Sex differences have been reported in objective interoceptive accuracy and self-reported interoceptive attention, yet the factors underlying such differences remain poorly understood. One theory is that these differences arise from increased amount of physical and hormonal change females experience across the lifespan. The menstrual cycle provides a compelling test of this hypothesis and here we present the first investigation of interoception across the menstrual cycle. Twenty females completed daily interoceptive accuracy and attention assessments across two consecutive cycles, alongside matched exteroceptive control tasks (ISRCTN registration: 99520723). Cycle phases were determined using the counting method, with ovulation confirmed via cervical mucus ratings and basal body temperature. Interoceptive accuracy was higher during the periovulatory phase compared with the perimenstrual phase. Interoceptive attention was highest during the perimenstrual phase compared to all phases, though fully explained by physical symptom burden. Cycle-related changes were unique to interoception and emerged only within a complete menstrual cycle, highlighting the potential role of between-cycle hormonal variability. These data provide the first evidence that interoception varies across the menstrual cycle, with implications for sex differences in interoception and mental health.