Researchers have found that stress hormone cortisol can make the difference between being a hero or a coward – in fact those who rise to the challenge don't experience cortisol rush of those who fall to pieces when the going gets tough.

"Certain people are cooler under pressure and perform very, very well. There're some individuals who when confronted with extreme stress, their hormone profile is rather unique. It doesn't reach the same peak as the rest of us.

"So we're all ready to scream in our chairs, but there are individuals who just don't get as stressed," 'The Daily Mail' quoted lead researcher Deane Aikins of Yale University as saying.

In their study, the researchers subjected soldiers to concentration camp simulations and other stressful situations to reach the conclusion – they found those who remained calm made less cortisol and more neuropeptide Y, a compound which counteracts the effects of the stress hormone.

The study, which has shown that by measuring hormone levels it is possible to predict who'll keep their cool under pressure, has caught the eye of the US military which believes it could be used to create the perfect soldier.

In fact, using the right cocktail of supplements, steroids and mind exercises, it might be possible to turn run-of-the-mill recruits into heroes, according to them.

"In combative service, you can't turn down anybody. The question is how do you get folks who aren't as cool in terms of stress turned up so they're perhaps comparable. That is the holy grail right now of the US Department of Defence.