A mug of coffee in the morning does two things for men – the caffeine in the drink helps sleepy heads emerge from nocturnal slumbers and also adds “potency” to sperm, according to new research from Brazil.

Coffee drinkers have more active sperm than those who never have the drink, researchers claim.

The findings suggest caffeine-based stimulants could help men with poor sperm movement.

Researchers led by Fabio Pasqualotto at the University of Sao Paulo examined the semen of 750 men at the university’s clinic for vasectomies, and evaluated the “swimming ability” of sperm.

Dr Pasqualotto said: “Sperm motility was higher in patients who drink coffee compared to patients who do not drink coffee.”

The study presented at the annual American Society for Reproductive Medicine conference in San Antonio Monday contended that coffee drinkers had stronger and more powerful sperm than non-drinkers.

Euan Paul of the Coffee Science Information Centre, said: “These findings are very exciting.

“If sperm don’t swim well they tend to be more lethargic – they give up before they reach their goal. It seems caffeine makes them swim faster.”