Women who are sexually satisfied are also happier, no matter their age, a new study suggests. It's not clear which causes the other, however.

You might be thinking, "Duh, better sex makes for a better mood." But in science, thinking something is true doesn't make it so. "A lot of the things we make assumptions about have never been documented," said study researcher Susan Davis of the Women's Health Program at Monash University, Australia.

While some might claim to have known a lady's sex life can affect her quality of life, Davis says the link is not always taken seriously. As such, when a guy cries "erectile dysfunction," doctors are quick with prescriptions and advice. But, the researchers point out, a woman's sexual desire, and lack thereof, may garner quizzical stares or even a "Who cares," Davis said.

Among the things scientists do know about women and sex: Women's most common complaints involve sexual desire and interest, as well as pleasure and satisfaction, the researchers say. The problems are often attributed to women's busy schedules (and so sex becomes another "task"); discontent with their own bodies; unwillingness to ask for what they want in bed; and other factors. At the end of the day, some women just settle for mediocre sex.

Whether boosting a women's sexual pleasure has any impacts beyond the bedroom has remained less clear, scientifically speaking.

The new study, detailed in the October issue of the Journal of Sexual Medicine, suggests there is, in fact, a strong connection.

Strengths and weaknesses

The study does have its limitations, including a relatively small number of study participants (nearly 300). In addition, the results only show a link between sexual satisfaction and overall well-being, but which factor (if either) causes the other can't be teased out by this study.

"The problem with interpreting this finding is that it is impossible to determine if dissatisfied women had lower well-being because they were sexually dissatisfied, or if the reverse is true, such that women who started with lower well-being tended to secondarily have sexual dissatisfaction," said lead researcher Sonia Davison, also of Monash's Women's Health Program.

One big positive, the study wasn't funded by a drug company, but rather by the National Health and Medical Research Council of Australia. Plus, the effect found was large, and for post-menopausal women the difference in well-being between sexually satisfied and dissatisfied women was statistically significant.

For instance, among post-menopausal women, those who reported sexual dissatisfaction scored 10 percent lower on an established "well-being" scale. Overall, the difference in well-being is similar to that found between healthy women and those with severe, chronic back pain, Davis noted.

Sexual stats

To get the scoop on the sex effects, Davis, Davison and their colleagues surveyed nearly 300 women ages 20 to 65, with about half who were pre-menopausal and half post-menopausal. More than 140 women reported they were dissatisfied with their sex lives, about equally split between the pre- and post-menopausal participants.

Over a 28-day period, participants recorded their daily sexual events. They also responded to questionnaires focused on well-being and sexual satisfaction.

The well-being scale included questions about anxiety, depression, cheerfulness, self-control, general health and vitality. Post-menopausal women showed the greatest difference in overall well-being between the two groups, with sexually satisfied women scoring nearly 84 on the questionnaire compared with 76 for the dissatisfied group. (Total points were out of 110.)

For post-menopausal women, those whose sex lives were in the dumps scored on average lower on questions related to anxiety, depression, positive well-being (cheerfulness) and vitality. Pre-menopausal women showed similar results, with the sexually dissatisfied scoring lower on vitality and positive well-being.

There was no real difference in other well-being factors, such as general health and self-control, regardless of age.

Beyond the bedroom

As for how sexual desire and pleasure can impact a woman's well-being, Davis suggests several reasons, including the effect on a couple's relationship and a woman's self-esteem. "They just don't feel as good about themselves," Davis said of women who lack sexual libido.

The results have various implications.

"The take-home message is that it's an important issue for women to talk to their doctors about, and it's okay to talk to their doctors about," Davis told LiveScience. "And it's an important issue for doctors to talk to their patients about."

She notes that doctors who treat a woman for depression may want to ask her about sexual and relationship satisfaction. That way, before writing out a prescription for an anti-depressant, a doctor could help the patient deal with an underlying issue with sex, Davis said.

Doctors might want to probe past the question of sexual intercourse frequency, the researchers point out, as both sexually satisfied and dissatisfied women may be equally likely to get intimate with their partners. For instance, more than 90 percent of participants reported their sexual activity involved a partner, and was initiated by the partner at least half the time. As such, women's sexual activity may have been the result of their partner's nudging or not-nudging as well as other factors not addressed in the current study, the researchers say.

"The fact that women who self-identified as being dissatisfied maintained the level of sexual activity reported most likely represents established behavior and partner expectation," Davis said.