As a sex researcher, I've been thinking about how much the World Cup players have been thinking about having sex – even if they aren't supposed to be participating in sexual activity.

The team-by-team rules governing players' sexual behavior during competition this year are varied, and the "evidence" that those rules matter is weak. But the round of 16 is nearly complete, and while no managers have sanctioned sex on the field, it would seem those countries that allow scoring off the field ... are still advancing in the tournament:

So, Team USA and England were allowed to go for unrestricted sexual goals, and we know those teams are going in opposite directions. But all the teams with public anti-sex policies at the World Cup have been knocked out. Much of whatever coaches think they know about the relationship between sexual release and athletic performance, however, is myth. What little actual scientific research has been done suggests that sexual activity the night before a game may be helpful if it results in relaxation and a good night's sleep, but there has been far too little research. Indeed, there is no evidence whatsoever that being in a sexually deprived state will help athletic performance.

There exists a stigma about research on sexual behavior – that it's unnecessary and perhaps even perverse, especially when the research is focused on sexual pleasure rather than on the prevention of sexually-transmitted disease or pregnancy. This, along with a lack of funding, likely accounts for the absence of much data on the impact of sexual activity on athletic performance ... and in a lot of other areas of life.

For example, what about the adage that men think about sex every seven seconds? Isn't there scientific evidence for that?

No, actually, there isn't. Nobody knows the origin of this myth, but it is astoundingly persistent, despite the fact that the few studies conducted on the prevalence of sexual thoughts have indicated that the frequency is nowhere near that much. My team's recent research indicates that young men asked to track their sex-related thoughts reported only one to two sexual thoughts per hour, the same frequency with which other men in the study thought about food or about sleep.

It says something about the paucity of sex research that our modest study of 120 men (and 163 women), using a very basic technique to gather data (plastic tally counters), and costing less than 10 soccer balls, is currently the best source of information about how often people think about sex.

Beyond smashing the once-every-seven-seconds myth, the most striking finding from our research was the huge variation from one person to the next. Daily reported frequency of thoughts pertaining to sex ranged from 1 to 388 for men and from 1 to 140 for women. Any attempts to generalize about the nature and frequency of thoughts in a person's head based on gender alone are likely to be inaccurate. So, too, is trying to predict the outcome of a game based on a coach's guidelines for sexual activity.

In 2000, Samantha McGlone and Ian Shrier suggested in the Clinical Journal of Sport Medicine that, in the absence of research-based evidence that sexual activity is harmful to athletic performance, what is likely most important the night before a sports competition is sticking with one's usual routine, whether that involves having sex or not. Additional research on the topic has been scarce, and so instead we have ill-informed opinions and superstitious policies.

Ultimately, it matters little whether players can engage in sex during the World Cup – or hook up all over the Olympic village – but the motley mixture of rules provides a microcosm of what can happen in the absence of solid data. When myths and stereotypes are more influential than research findings, misconceptions get perpetuated. A man who believes he is supposed to be thinking about sex constantly might feel there is something wrong with him if he doesn't. An athlete who believes his team will lose if he engages in sexual activity could become a victim of a self-fulfilling prophecy.

Why not attempt to address these everyday (and night) issues by funding and supporting more and better empirical research on sexuality? It would be a big score – not just for athletes and sex research but an important goal for anyone who believes that sex is a healthy part of life. And there would certainly be no shortage of volunteers to participate in the research.