If your acne gets worse when you're stressed, here's why: Anger, depression and anxiety affect the immune system, which can cause or aggravate skin troubles. Now, the up-and-coming field of psychodermatology explores this mind-body connection.

Ted A. Grossbart, a Harvard Medical School psychologist and author of Skin Deep: A Mind/Body Program for Healthy Skin, says that "30% to 60% of people who see a doctor for a skin problem have emotional issues, so they're not likely to get the results they hope for from the best conventional medical care." 

Sometimes, using medication or talk therapy to treat psychological symptoms may improve the skin condition. Other times, mind-body techniques for general relaxation and stress reduction have a healing effect.

"And sometimes, just being aware of what triggers your skin problems can help you zero in on what may be bubbling up under your skin," Grossbart says. "If you feel it in your heart, you don't have to feel it in your skin."

Conditions most closely linked to emotions: acne, eczema, herpes (oral and genital), hives, psoriasis, rosacea and warts.

Alternative treatments that provide the best results: biofeedback, hypnosis, guided imagery, mindful meditation and psychotherapy.