By Beverly Herzog

Strengthen a weak immune system.
Having sex increases the body’s level of Immunoglobulin A (IgA), an infection-fighting antibody. “IgA is the first line of protection against the entry of pathogens,” says Carl Charnetski, PhD, co-author of Feeling Good Is Good For You: How Pleasure Can Boost Your Immune System and Lengthen Your Life (Rodale Books, 2003). And you don’t have to get it on every night to see results, either. “There was a 30 percent increase in IgA in those who had sexual activity once or twice a week,” says Chartnetski.

Ease vaginal atrophy.
According to a recent Harris Interactive survey, 75 percent of women who experience this menopause-related symptom, which causes dryness and painful intercourse, respond (not surprisingly) by cutting back on sex. But having sex more frequently can actually reduce pain by enhancing blood flow to the area, which keeps vaginal tissue healthy, says Murray A. Freedman, MD, of Augusta GYN and clinical professor at the Medical College of Georgia.

Make migraines disappear.
Find it hard to believe that sex might be nature’s remedy for one of these splitting headaches? A study by Timothy Houle, PhD, research assistant professor of anesthesiology at Wake Forest University School of Medicine, found that migraine sufferers typically have low serotonin levels. Since sex boosts serotonin, it can mean fewer migraines.