Autonomic Nervous System, Cognition, and Emotional Valence During Different Phases of the Menstrual Cycle-A Narrative Review.

The menstrual cycle affects the autonomic nervous system (ANS), cognition, and emotional valence in all biological women. There exists a complex relationship between hormonal fluctuations, ANS, cognition, and emotional valence during the different phases of the menstrual cycle, which includes menstruation, the follicular phase, ovulation, and the luteal phase. Hence, this narrative review is an attempt to comprehensively understand the effects of the menstrual cycle on the structural and functional integrity of the ANS. In order to provide a comprehensive understanding of the complex relationship between the menstrual cycle, hormonal fluctuations, and ANS function in biological women, this review examines key parameters, including heart rate variability (HRV), baroreflex sensitivity (BRS), muscle sympathetic nerve activity (MSNA), and pupillary light reflex (PLR), to investigate how these physiological systems are dynamically influenced by the cyclical changes in hormone levels and how these fluctuations impact various physiological and psychological outcomes, such as mood, cognition, and emotional regulation. There have been several studies previously performed to assess these parameters during different phases of the menstrual cycle. However, the results have been contradictory; therefore, this review explores possible reasons behind these inconsistent results, with likely reasons including irregularity in the menstrual cycles and differences in hormonal fluctuations between different women during similar phases of the menstrual cycle. Overall, there appears to be evidence to suggest that the menstrual cycle has both direct and indirect effects on ANS, cognition, and emotional valence, whilst measures of ANS may provide a means for assessing the effect of the menstrual cycle.