The British Psychological Society blog points to a study by Lindsay St. Claire and colleagues that suggests coffee is bad for men who are trying to collaborate or negotiate in stressful circumstances. The study found that the caffeine undermined their performance and confidence.
Interestingly it found that coffee had a beneficial effect for women in the same circumstances. The researchers think this could be because women tend to respond to stress collaboratively, whereas men tend to ‘fight or flight’.
The study found that men’s memory performance under stressful conditions with caffeine were ‘greatly impaired’:
For the construction puzzles, caffeine under high stress conditions led men to take an average of twenty seconds longer (compared with no caffeine) whereas it led women to solve the puzzles 100 seconds faster.
The study acknowledges some shortcomings, but concludes that further research is clearly needed, and urgently:
…because many … meetings, including those at which military and other decisions of great import are made, are likely to be male-dominated. Our research suggests that men’s effectiveness is particularly likely to be compromised. Because caffeine is the most widely consumed drug in the world, it follows that the global implications are potentially staggering.