Sure it can. You tense and release lots of muscles and that can lead to relaxation and a feeling of well-being. Having sex also releases endorphins and other "feel good" substances in your brain. It is harder for a woman to achieve an orgasm when she is stressed, so start with a massage as part of foreplay. People with a good sex life benefit in many ways including longevity. On the other hand, don't just go pick someone up to get rid of your stress. AIDS, unwanted pregnancy, risky behavior, getting hurt by a stranger, etc. are all very stressful, so the casual sex could be self-defeating! A long walk or a good work-out can accomplish many of the same things and won't backfire on you emotionally. Check out some of the health websites for ways to deal with stress such as meditation, exercise, and affirmations. Cut-out the caffeine and nicotine. A glass of wine can help you relax, but don't drink too much because alcohol is a depressant.