Tests on more than 100 undergraduate students finds narcissistic men tend of have higher levels of the stress related hormone cortisol. It can have some benefits, lending an energy surge, helping the body burn fat and boosting memory.
But too much cortisol from chronic stress may contribute to high blood pressure and lower immunity.
Researchers speculate that those with unhealthy narcissism may feel stress and act more aggressively when they think their ego and perceived authority are threatened.
There is more on this in the journal PLoS ONE.
