Researchers at the University of Barcelona found that the effects of caffeine work faster in men than women, BBC News reported.
The study, which is published in the journal Progress in Neuro-Psychopharmacology & Biological Psychiatry, looked at 668 healthy participants.
The volunteers were asked to drink either a classic espresso, which contained 100 milligrams of caffeine or a decaffeinated espresso, which contained 5 milligrams of caffeine.
After drinking an espresso, the men were “peppy” after just 10 minutes.
The researchers said the women also seemed alert, but the effects were not the same as those of the men.
Researchers said 45 minutes is needed after drinking a cup of coffee, as that is how long it takes for all of the caffeine to absorb in the bloodstream.
“Numerous studies have demonstrated the stimulant effects of caffeine, but none of these have looked at their effects in terms of the consumer’s gender,” lead researcher Ana Adan said.
Experts said this kind of research could one day lead to dietary recommendations based on genetic make-up, body size and age.