Where there’s dope smoke, there’s more bedroom fire

The ancients knew the power of cannabis. An early Western traveller to India wrote how the drug was taken to give locals ‘‘intense aphrodisiac desire’’. In the Middle East, a passage in Arabian Nights asked: ‘‘Art thou not ashamed, O hashish-eater, to be sleeping stark naked with stiff-standing tool?’’

Now science has confirmed it – people who smoke marijuana do have more sex.

Researchers at Stanford University have used a lifestyle survey of 50,000 adults aged 25 to 45 to assess the effect of the drug on sexual activity.

Many modern doctors had assumed that the drug would have a dampening effect on desire, impeding sexual functioning. The latest work, published in The Journal of Sexual Medicine, found the reverse.

‘‘Frequent marijuana use doesn’t seem to impair sexual motivation or performance. If anything, it’s associated with increased coital frequency,’’ said Michael Eisenberg, from Stanford University School of Medicine, who led the study.

Whichever group he and his colleagues looked at – married, young, old, educated, unhealthy or healthy – they found the same pattern. When the researchers compared people’s reported cannabis use with their reported sexual activity, the two rose together.

Regular users had roughly a fifth more sex. Women who had used the drug daily had sex 7.1 times. For men, the figures were similar: 5.6 versus 6.9.

The study could not say why this was or confirm that one caused the other. ‘‘It doesn’t say if you smoke more marijuana, you’ll have more sex,’’ Eisenberg said. It could be, for instance, that those who smoke cannabis are also the sort of free and easy people who would have more sex anyway.

However, when the researchers looked at other illegal drugs, such as cocaine, they found no such link. This implied that the effect really might be caused by the cannabis itself.

While this is good news for adults who regularly smoke cannabis, it does not change the fact that there remain other health consequences from using the drug, including a link to schizophrenia.

Separately, there have been studies showing reduced sperm counts among heavy smokers – and, contrary to Arabian Nights, reports of erectile dysfunction.