In the midst of controversy over whether or not a female Viagra should be made available to women, US researchers say we could be overlooking one basic element that could play a role in her desire: sleep.

"The influence of sleep on sexual desire and arousal has received little attention in the field, but these findings indicate that insufficient sleep can decrease sexual desire and arousal for women," says lead author Dr. David Kalmbach.

Although research exists suggesting that not getting enough sleep in both duration and quality can diminish female sexual response, the relationship between sleep and sex for women needs to be prospectively examined, says Dr. Kalmbach.

In the study, the research team observed 171 women and concluded that those who slept more on a given night saw a boost in their desire the following day.

Each additional hour of sleep increased the likelihood of sexual activity with their partners by 14 percent.

Sleeping too much, however, appeared to diminish genital sensitivity the next day, however those who slept more on average reported better genital sensitivity.

Subjects were recruited from a US university and were not taking antidepressants, according to the study, of which the experimental period lasted 14 consecutive days.

They were asked to respond to a questionnaire in which they described their subjective arousal, which is a term for arousal in the absence of genital stimulation that originates from sexual thoughts.

The questionnaire also asked them to rate their individual sexual response in terms of both genital arousal as well as orgasmic functioning and to indicate what led them to engage in sexual activity -- be it with a partner or solo.

"I think the take-home message should not be that more sleep is better, but that it is important to allow ourselves to obtain the sleep that our mind and body needs," says Dr. Kalmbach.

Given that sleep problems and sleep disorders are increasingly common, Dr. Kalmbach says more research is needed on their relationship to sexual disfunction.

The study was published in the Journal of Sexual Medicine.