Dr Petra Boyton casts a critical eye on recent media stories suggesting that sex on first date releases ‘brain hormones’ that increase trust and intimacy that might improve the long-term chances of a relationship. So what does neuroscience tell us about the link?
The claim is made by Dr Barry Gibb [insert Bee Gees joke here] in a new book The Rough Guide to the Brain.
The claim is likely based on the fact that the hormone oxytocin has been reported to increase trust in humans when deliberately administered by experimenters, and has been linked to sexual response in humans.
The trouble is, the evidence for a strong and consistent link with sexual response isn’t really there yet.
A recent review article examined the role of hormones in sexual arousal and looked specifically at oxytocin, noting that:
Carmichael et al. (1987) found that plasma OT [oxytocin] increased around the time of orgasm in men and women, remaining raised for at least 5 min after orgasm…. In a recent study of men, OT increased in some subjects following ejaculation, but the individual variability was such that the group effect was not significant (Kruger et al. 2003a).
Murphy et al. (1987) reported an increase in OT in men during sexual arousal, which persisted beyond ejaculation, but with no obvious increase at ejaculation. In a study of women, Blaicher et al.(1999) found an increase in OT 1 min after orgasm, but levels were close to baseline by 5 min post-orgasm.
It is difficult to draw clear conclusions from this literature on OT and sexual arousal. Whether the increase of OT around orgasm, which has been somewhat inconsistently observed in the human literature, has any specific function, rather than being an epiphenomenon of other changes, remains uncertain…
In other words, the evidence for oxytocin being released consistently during sex is mixed and its significance is unclear.
Even if sex and the oxytocin ‘trust boost’ was reliably linked, you would need to do a study looking at whether couples trust each other more after having sex for the first time to really be sure whether the effect actually had an impact.
Sex causes such a strong behavioural, psychological and neurochemical change that a small release of oxytocin might be completely insignificant among the storm of other effects.
So does sex on first date increase the chances of a long-term relationship?
We don’t know, and what we do know about the neuroscience of sexual response doesn’t really tell us either.
UPDATE: Susan Kuchinskas has added some insightful commentary to this post. Check the comments section.