A woman's heart rate may indicate if she has a low sex drive. A study at the University of Texas found that women with a low heart rate variability (HRV) — the variation in time between heartbeats — is linked to low libido.

Average or high HRV has been associated with healthy hearts and improved blood flow to the genitals.

Those with low HRV are dominated by their sympathetic nervous system — the body's fight or flight response — which is easily stimulated and stays active constantly. Previous studies have associated low HRV with several mental conditions, including anxiety, depression, and alcohol dependence. Studies have also hinted that an easily stimulated nervous system hinders arousal, and is linked to erectile dysfunction in men.

On the other hand, average or high HRV has been associated with healthy hearts and improved blood flow to the genitals. Researchers theorized that low HRV was linked to sexual dysfunction in women.

Researchers analyzed HRV and self-reported information from 72 women aged 18 to 39 using the Female Sexual Function Index to evaluate their overall sexual functioning. The questionnaire included categories such as pain, satisfaction, and desire.

They found that in addition to overall sexual dysfunction, women with below average HRV were more likely to have difficulties with sexual arousal.

"The Female Sexual Function Index has been shown to effectively identify women with clinically significant levels of sexual dysfunction," said co-author and UT Austin psychologist Cindy Meston, who helped develop the index in 2000.

"There is also an emotional component to all of this," lead author Amelia Stanton told Live Science. "Low HRV has been associated with blunted emotional responses. So both blood flow and emotional responding play large roles in female sexual function."

"Because HRV has been related to many negative mental health and cardiac problems, it’s interesting to bring an established clinical marker into sex research," Stanton. "It allows us to look at the issue of sexual dysfunction in women in a different way."

"Because evidence shows that low HRV is a potential risk factor for sexual dysfunction, physicians have a simple, low-cost and nonintrusive method to measure a woman’s risk for sexual dysfunction," said Stanton. "It makes it easier to talk about something a little bit more private and get women the help that they need."

"In women, genital arousal is mediated by some of the same mechanisms as genital arousal in men," the authors wrote in their study, which was published in Applied Psychophysiology and Biofeedback.

In addition to evaluating a woman's risk for sexual dysfunction, researchers believe that HRV could also be used to evaluate the effectiveness of drugs to used to treat the condition.