‘Shyness has a strange element of narcissism, a belief that how we look, how we perform, is truly important to other people,” said Andre Dubus in 1991. He may have been exactly right when he said this, in light of recent psychoanalysis studies. Researchers in America and abroad have discovered that both narcissistic and introverted personality types are most likely to gravitate to one common, self-indulging oasis: Facebook.

Narcissism takes refuge in the digital world. It hides behind friend requests, ‘likes,’ and status updates on Facebook. It lurks in tweets, photo albums and ‘About me’ blurbs. Worst of all, it disguises a real human being to others — and even to themselves.

A Cornell University study from February 2011 found that people with narcissistic personalities are more likely to use Facebook, a link they attributed to the ego boost narcissists get from being liked online. The networking site gives them their own reality TV show, written by them and starring them, but produced by Facebook, in which they can share every mundane detail about their lives and receive praise on it. They can present themselves in the best light, crafting every detail of their public image down to the flattering angle of their carefully chosen profile picture.

Extreme cases of this Facebook self-promotion have even made it onto national news stations. A YouTube video shows Dana Hana updating his Facebook status at the altar while a priest reads him his wedding vows. Another couple became famous for their marriage: Kelly Hildebrandt and Kelly Hildebrandt met on Facebook after searching for someone with the same full name. A boy from Ecuador convinced 50,000 users to join a Facebook group in 24 hours by promising to tattoo all 150 original Pokemon characters on his back if the group reached one million members. Changing his mind, the young man removed his profile from Facebook soon afterward. Now there is a group of 600,000 users looking for this one-time center of attention. But these narcissists are not the only ones online.

Counter-intuitively, individuals with low self-esteem comprise the second largest personality type among Facebook users, according to the Cornell University study. Social media offers people who find interpersonal contact uncomfortable or even terrifying a “safe” outlet for interaction. Users with low self-esteem are encouraged by the opportunity to connect and seek approval without the risk of face-to-face rejection.

However, introverts may not find the popularity they crave online. The same study found that posts made by people with low self-esteem tended to be negative in tone, and their Facebook friends tended to ignore those posts. The study speculated that introverts did not garner attention because friends saw their messages in the context of the user’s withdrawn personality.

Introverted people are more vulnerable to the psychological stress caused by the need for validation on Facebook, and this can be accelerated to dangerous levels — ones that we can no longer laugh off as simple acts of self-absorption. Last month in Iowa, for example, a woman was arrested for setting her neighbor’s house on fire after she un-friended her on Facebook. In another incident, a Texas man was convicted of battery after he violently attacked his wife for failing to ‘like’ his new status. In some cases, Facebook anxiety develops into physiological, rather than psychological, distress. Doctors in Naples, Italy identified a link between Facebook and asthma attacks when they realized the asthma attacks of an 18-year-old patient were brought about by viewing his ex-girlfriend’s profile page.

Both personality types, however, face the threat of losing personal information on Facebook, because self-disclosure is a natural human signal for the need of social support. People who are desperate for affection are more likely to make their profile visible to the public, and thus more susceptible to violation. A study conducted at University of Guelph, a Canadian university, found a positive correlation between levels of Facebook disclosure and a need for popularity. By contrast, those with more protected profile security settings tended to have higher self-esteem. Those with low self-esteem, the ones most desperate for online friends, are also most susceptible to harm from privacy exploits.

And the privacy dangers of Facebook are real. The “SocialBot Network,” a British Columbia-based security system analyst designed especially for Facebook, ran a test to show the holes in Facebook’s supposed privacy wall. In one of its first experimental runs, the program created 250 SocialBots that garned over 250 GB of private information from thousands of successful friend requests. The Facebook security system found only 20 of them. Soon Google will add to the problem with its new “Spiders” program, which will index all comments that you post on Facebook-linked websites. Web users will be able to simply type in your name and part of one of your comments to gain access to not only that comment, but all of the comments that you post on enabled websites.

These drawbacks might tempt you to go into a Facebook lockdown, blocking any potential SocialBot, stalker or crazed arsonist. It’s not a bad idea. But there is an easier option to protect your own mental and physical safety. Go ahead and sign in this week, but do so with a healthier perspective toward social networking sites. Understand that you are not defined by the number of Facebook friends, Twitter followers or status ‘likes.’ Remember that no complete identity is derived from an online social context. Finally, remind yourself that having a “friend” is being a friend. Instead of ignoring friends with negative status messages or a withdrawn attitude, reach out to them. Give them the affection that they log onto the website for.