Grabbing the sheets
The female orgasm is not straightforward to study Getty

In an attempt to move the debate over the female orgasm on from 'clitoris versus the vagina', psychologist Jim Pfaus at Concordia University in Canada argues that the question should be reframed to consider the whole body.

In a paper published in Socioaffective Neuroscience and Psychology, Pfaus argues that historic arguments over the relative importance of clitoral orgasms and vaginal orgasms is hindering research on the female orgasm, which differs from the male orgasm in important ways.

"Stimulation of one or all of these triggering zones are integrated into a whole set of sensory inputs, movements, body positions, arousals and cues related to context," Pfaus says. "That combination of sensory input is what reliably induces pleasure and orgasm during masturbation and intercourse."

While Pfaus argues for more research on integrating these various factors in the study of the female orgasm in particular, another paper in the special issue of the journal – Orgasm: Neurophysiological, Psychological, and Evolutionary Perspectives – argues that orgasm in both men and women amounts to an altered state that can be likened to a trance.

The rhythm of sexual activity has a synergistic effect on neural oscillations in the brain, according to Adam Safron, a psychology PhD student at the Weinberg College of Arts and Sciences at Northwestern University in the US.

Safron argues that when rhythms of stimulation and of oscillations in the cortex coincide in frequency they amplify each other. This positive feedback, or virtuous circle, is what enhances "perceptual vividness and emotional intensity" during sex, leading to a state that he likens to a trance state, he says.

"The idea that sexual experiences can be like trance states is in some ways ancient," Safron says. "In theory, this could change the way people view their sexuality. Sex is a source of pleasurable sensations and emotional connection, but beyond that, it's actually an altered state of consciousness."

Saffron argues that being capable of switching between multiple rhythms and inferring the best times for these changes plays an evolutionary role in mate-selection in humans, testing motor skills as well as social intelligence.

However, the studies necessary to put Safron's model to the test may be a long time coming. Ethical approval and funding for such studies can be difficult to obtain, as experienced by researchers such as neuroscientist Nicole Prause of the Liberos Center in Los Angles.

Prause previously told the Guardian that she had had her lab stopped from studying orgasms while at the University of California, Los Angles. "They basically said you are not allowed to know," she says.