How it works: For starters, yoga reduces cortisol by relaxing you. "Nasty stress hormones only aggravate pain," Field says. Yoga also promotes better sleep, and the more soundly you snooze, the fewer pain chemicals your brain secretes.
Which type to try: As with treating back pain, pick a calming practice, Dr. McCall advises. Zenning out in a long Savasana (Corpse pose) at the end of class will help. So will focusing on exhalations. If it feels good, make each twice as long as your inhalations.
Depression
What we know: People on antidepressants who added thrice-weekly yoga for two months said they felt less depressed, anxious and angry, University of California Los Angeles research notes. In 65 percent, their depression went into remission.
How it works: Your hormones are at work here, too. "Yoga helps your body produce serotonin, a natural antidepressant, and helps lower cortisol levels, which are elevated in people with depression," Field says.
Which type to try: If you're in a slump (but still fairly fit), energizing poses such as Sun Salutations may lift you out of it. "There's a misconception that yoga is only about relaxation," Dr. McCall says. "Some practices can stimulate you."
Eating Disorders
What we know: Could a yogi heal your eating issues? In a recent study of 50 adolescent girls with eating disorders, scientists found that an hour of yoga a week for eight weeks reduced subjects' symptoms and their overall preoccupation with food.
How it works: Anxiety and depression pop up more often in people with eating problems, says study coauthor Amber Frye-Johnson, a research scientist at Abbott Northwestern Hospital in Minneapolis. Yoga fans have lower rates of both.
Which type to try: "All yoga makes people more accepting and loving toward themselves and their body," Dr. McCall says. You may need a relaxing or energizing class based on symptoms. Consult your doctor and YogaAlliance.org to find the right one.
Chanting With the Stars (and More la-la Moves)
Mel B.
Treatment Reiki for Stress
What she says: The former Spice Girl says Reiki—in which a healer lightly touches you, supposedly transferring energy—helped her cope during the delivery of her youngest daughter, now 3. "Sometimes you can create lots of panic and problems," she told British OK! "I think [Reiki] helped me relax."
What science says: Try it if you'd like, but don't count on major results. A 2008 review in the International Journal of Clinical Practice found that there aren't enough solid studies to show that Reiki works. Still, the lying still for 30 to 90 minutes part of the therapy may help you chill out, which could lower your blood pressure and heart rate.