02/09/2012 02:58 pm ET Updated Apr 10, 2012

Big Men on Campus, Beware: Your Ego May Be Harming You

Mirror, mirror, on the wall, who's the sickest of them all? A new study says it might be the guys who are always looking in the mirror!

We all remember those guys who were popular the second they walked into a room. They were probably also the "love 'em and leave 'em" type who seemed too cool for just about everyone.

Psychologists call this personality type narcissism, which describes people who feel self-important and constantly need to stand out in a crowd. And although Narcissistic Nick usually makes a huge splash at the party, he's a far less desirable romantic partner because he "plays games," prefers people who boost his ego and has trouble with commitment.

Sound familiar, ladies?

But if all of this reminds you of an old flame you'd rather forget, perhaps what goes around does come back around. That's because researchers have discovered that some men who score higher on a narcissism personality test may also have significantly higher levels of the stress marker cortisol in their saliva, according to a new study of around 80 female and 30 male college-age students. But what does the big man on campus have to worry about? Having too many friends?

Some psychologists think that behind the big ego might actually be a ball of insecurity and self-doubt. That's why these guys surround themselves with people who elevate their confidence, and why they get defensive when they sense their dominance is threatened. So narcissism could be a way of coping with stressful feelings of inferiority. And what happens when you're always stressed about what people think of you? Your body pumps out more cortisol!

What's the link with health? One of cortisol's effects in the body is to suppress the immune system, which normally defends us against illness and infection. For Narcissistic Nick, whose stress levels are always up, this could mean he gets sick more, as well. Even when the researchers took into account differences in a guy's mood, social support system or relationship status, narcissistic men still had increased cortisol levels, especially those who scored higher in "unhealthy" traits like feelings of entitlement.

Although we can't always control our personalities, we can try to understand why we're feeling the way we're feeling. Stress-reducing strategies like eating a balanced diet, doing regular physical activity and getting enough rest every night can help us stay focused and healthy, even when the going gets tough.

Now here's the kicker: The researchers didn't find any difference in the cortisol levels between narcissistic and non-narcissistic women. Fairest of them all, indeed!

For more by John Whyte, M.D., MPH, click here.

For more on new research, click here.