Normally, you keep secrets to save yourself or others embarrassment, shame, or emotional pain. Perhaps you fear you or others will be shunned or abandoned. Then again, you may agree to secrecy out of kindness (keeping your impending divorce from your dying mother) or to foster a bond with someone (vowing not to tell a soul about your friend's facelift).
While a secret can unite, it also can divide. Your feelings of guilt can distance you from others. Someone who suspects you're hiding something may not trust you and may harbor a secret in turn. Family secrets can estrange relatives and cause painful communication trouble, Dr. Imber-Black says.
Keeping secrets "can also make you ill," says Dr. Wegner. "When you have a secret, you try not to think about it or feel the emotions connected with it. But by attempting to suppress your thoughts and emotions, you end up being obsessed by them instead. This produces stress, which can lead to long-term health problems."