Female Sexual Function and Heart Rate Variability

Abstract

Few studies have examined the associations of resting heart rate variability (HRV) with female sexual function and behavior. Therefore, we welcome the recent study finding that women with below average resting HRV (as assessed by the standard deviation of NN intervals; SDNN) had lower sexual arousal and lower global sexual function than women with average or above average SDNN (while viewing a neutral film) (Stanton et al. 2015). The SDNN reflects relatively lower sympathetic activity and/or relatively higher parasympathetic activity. Those authors noted the lack of studies on female sexuality and HRV, but missed citing an important study which explored the associations of HRV with women’s frequency of orgasm produced by several different sexual behaviors (Costa and Brody 2012). In that study, it was found that women who had any orgasm triggered by penile-vaginal intercourse (PVI) without simultaneous clitoral masturbation (henceforth, vaginal orgasm) in the past month had higher resting HRV (as assessed by the standard deviation of heart rate, a relatively similar index of HRV) than women who did not have a vaginal orgasm in the past month (Costa and Brody 2012). Of note, orgasm produced by other sexual behaviors including PVI with concurrent clitoral masturbation for the orgasm, clitorally-focused partnered masturbation, oral sex, solitary masturbation, and anal sex were unrelated to resting HRV. Orgasm from vaginally-focused masturbation by the woman’s partner was nearly significantly associated with higher HRV, but this marginal association disappeared in multivariate analyses controlling for the other orgasm trigger frequencies, resulting in only vaginal orgasm being associated with women’s greater resting HRV. These findings were discussed in terms of lower HRV being a reflection of pathophysiological processes that can impair female orgasmic responsiveness specifically during PVI (Costa and Brody 2012). This raises the possibility that vaginal responsiveness is more easily adversely affected by psychological and physiological dysfunctional processes than responding to direct clitoral masturbation. The vagus nerve (the main driver of the parasympathetic nervous system influences on HRV) transmits afferent sensory information from the proximal vagina and cervix to the brain, but is not stimulated by the clitoris (Komisaruk and Whipple 1998; Komisaruk et al. 2004). Given that appropriate afferent vagal stimulation might increase (or ‘‘tune’’) efferent vagal activity on a relatively long-term basis (Gellhorn 1967), it is plausible that PVI may enhance HRV with concomitant health benefits (Costa and Brody 2012). These findings are congruent with another study finding that greater resting HRV (standard deviation of heart rate) was associated with greater PVI frequency in a sample of both sexes, and the sex of the research participant was not a significant confounding variable (Brody and Preut 2003). Unlike in the study by Stanton and colleagues, in these two studies, resting HRV was measured without an inserted vaginal probe (Brody and Preut 2003; Costa and Brody 2012), which Stanton and colleagues listed as a potential confounder in their own study. In a large nationally representative Czech sample, female sexual arousal disorder was related to lack of history of vaginal orgasm and difficulties in focusing on & Rui M. Costa rmscosta@gmail.com