Let’s face it. If alcohol didn’t exist, many of you probably wouldn’t either. It’s a pretty important sexual lubricant: it gets people together, it gets them chatting, it gets them flirting, it gets them home in a cab, then it gets them naked. But sometimes, after it’s done all this good work to ready you for coitus, it lets down one of the key players – literally.

In Macbeth, the wise Porter told Macduff that drinking: “provokes the desire, but it takes away the performance… it makes him stand to, and not stand to; in conclusion, equivocates him in a sleep, and, giving him the lie, leaves him.” Basically, it makes you lose your boner.

Why does this happen? And is there a style of drinking that will still provoke the desire, but leave the performance well alone?

The American Urological Association says it’s all about how much you drink: “alcohol in small amounts improves erection and increases libido because of its vasodilatory effect and the suppression of anxiety”. A vasodilator is a drug that causes dilation of blood vessels, so when you’ve had a few drinks your blood swells up and helps your penis do the same. Couple that with reduced anxiety and you’ve got mojo-a-go-go.

But these positive effects only belong to moderate drinkers: “large amounts [of alcohol] can cause central sedation, decreased libido and transient erectile disfunction”. In this study, men who’d had a ‘large amount’ of alcohol gained significantly less peak circumference change from baseline – flaccid – than did sober men. And what these researchers call a large amount is what you or I would call a slow night – 4 or so beers. So really, there’s only a small window of quality time your penis can spend with your alcohol before things start to go sock-shaped.

The sad thing is that drunk men still want to have sex just as much (or more) than usual. When participants were drunk – above 4 drinks – they reported either no change or an increase in self-reported arousal levels. So what should you do when your spirit is keen, but your wiener is weak and spongey?

A recent study showed that concentrating hard on getting hard doesn’t work so well – what you need to do is focus on getting aroused. William George, of the Department of Psychology at the University of Washington, found that men who tried to maximize their sexual arousal – rather than shooting straight for an erection – “achieved a significantly higher peak percentage circumference change from baseline” than those who didn’t.

So guys – they say a watched pot never boils, so don’t keep too close an eye on your penis. Concentrate on what’s in front of you and get that blood pumping to your brain, so you can get it pumping down below.