A study by psychologists at Bristol University found drinking caffeinated coffee boosts a woman’s performance in stressful situations but has the opposite effect on men.
They become less confident and take longer to complete tasks once they have downed several cups of coffee.
The findings, published in the Journal of Applied Social Psychology, suggest the beverage may have radically different effects on the sexes in high-pressure situations.
According to the British Coffee Association, UK consumers drink approximately 70 million cups of coffee a day.
Some of the potential health benefits include protection against diabetes, Alzheimer’s disease, liver damage and even gout.
Caffeine in coffee is a known stimulant which works on the brain and can combat drowsiness and fatigue.
But researchers wanted to examine what coffee does to the body when it is already under stress, especially when large quantities are consumed in high-pressure meetings.
They recruited 64 men and women and put them in same-sex pairs. Each pair was given a range of tasks to complete, including carrying out negotiations, completing puzzles and tackling memory tasks.
To add to their stress, they were told they would also have to give a public presentation relating to their tasks.
Researchers then gave the pairs either caffeinated or decaffeinated coffee and monitored them throughout the experiment.
They found the men’s ability to perform well under stress was ‘greatly impaired’ if they had drunk the caffeinated coffee.
For example, they took an average of 20 seconds longer to complete puzzles than those on the decaffeinated coffee.
Women, on the other hand, completed them 100 seconds faster if they had been given caffeine.
Experts think the key to coffee’s effects on the sexes lies in the way men and women respond differently to stress.
Men are inclined to exhibit ‘fight or flight’ behaviour, whereas women are more inclined to work together to solve the problem they face, something psychologists call ‘tend and befriend’.
In a report on their findings the researchers said unlimited coffee supplies at high-level meetings might not be a good idea, especially for men.
"They might unintentionally sabotage the partnerships forged to solve stressful issues," the report said.
"Many such meetings, including those at which military and other decisions of great importance are made, are likely to be male-dominated.
"Because caffeine is the most widely consumed drug in the world, the global implications are potentially staggering."