Researchers have long assumed that the reason why men typically desire sex more than women was because men had higher levels of testosterone. 

However, a new study revealed that while women with higher levels of testosterone had greater desire to masturbate compared to their peers, they were less interested in having sex with a partner.

Scientists from the University of Michigan also found that in men testosterone levels did not appear to be associated with the desire to masturbate or have sex with a partner.

Researchers say that the findings suggest that there is a complex web of factors including anxiety that contributes to human sexual desire.

"People have argued that sex research focuses too much on dysfunction and pharmaceutical treatment as opposed to questions like pleasure or relationships or stress," lead author Sara M Van Anders from the University of Michigan said, according to Live Science. "There is a whole scope of factors that go unstudied."

Van Anders said that the latest findings are unique because it was one of the few to study healthy adults, while most other researches into sexual desire and hormones have used either animal models or patients being treated for abnormally low or high hormonal levels.

The study consisted of 105 men and 91 women who were asked to complete questionnaires about their sex lives, relationships, their stress and moods and their feelings about their body, answering questions like "Are you self-conscious about your body during sex?"

Participants also provided a saliva samples which the researchers used to measure their testosterone and stress hormone cortisol levels.

Both men and women have testosterone, a steroid hormone that is released by the ovaries in women and testes in men. Small amounts are also released in the adrenal gland in both sexes.

Researchers found that testosterone levels had nothing to do with how often men thought about masturbation or sex, even though women with higher testosterone were less likely to want to have sex with someone but more likely to masturbate.

Van Anders said that the latest findings fit with results from previous research that found that women in long-term relationships have lower levels of testosterone, which could mean that lower levels of the hormone drives women to find a partner to be close to rather than just to have sex with.

She suggests that higher testosterone could also reflect higher stress in women because the adrenal glands, which release the hormone, go into overdrive during stressful times.

Of all the women in the study, women who reported the most solitary sexual desire had the highest level of testosterone while women who reported no desire to masturbate had the lowest levels of testosterone, suggesting that the desire for a partner is more influenced by social factors and that solitary desire is more innate.

"These findings complicate our understanding of desire, by showing that two aspects of desire that are linked and thought to be relatively overlapping demonstrate opposing physiological correlations in women. They may provide an important foundation for modeling associations between T and desire, and for establishing additional dimensionalities to desire," the authors wrote in the study.

"Results from this study thus add to a growing body of literature highlighting the importance of measuring hormones and psychosocial variables in conjunction to address basic assumptions of human sexuality, gender and sex," they concluded.

Researchers found no evidence that links masturbation to sexual desire. While men were more likely to masturbate, they also report a greater desire to have sex compared to women.

"When you're saying you desire sexuality with another person, what are you desiring and are people desiring different things sometimes?" van Anders said, according to Live Science. "Are some people more desiring to be with their partner, to give their partner pleasure, to have a routine, or for their own pleasure?"

Van Anders said that the next step was to get a better understanding of the concept of desire, whether it triggers masturbation or vice versa, and to focus more on social factors rather than just pharmaceutical fixes for low libidos.