Alex Korb Ph.D. writes in his book entitled “The Upward Spiral”: “The results are fairly clear that massage boosts your serotonin by as much as 30 percent. Massage also decreases stress hormones and raises dopamine levels, which helps you create new good habits… Massage reduces pain because the oxytocin system activates painkilling endorphins. Massage also improves sleep and reduces fatigue by increasing serotonin and dopamine and decreasing the stress hormone cortisol.”
In the same vein, this is taken from the abstract of a meta-analysis of Massage Therapy (MT) research: “Single applications of MT reduced state anxiety, blood pressure, and heart rate but not negative mood, immediate assessment of pain, and cortisol level. Multiple applications reduced delayed assessment of pain. Reductions of trait anxiety and depression were MT’s largest effects, with a course of treatment providing benefits similar in magnitude to those of psychotherapy.”
If you’re ever interested in finding out more about the effectiveness of any treatment/modality/drug/supplement, PubMed is always a good place to start. Meta-analyses are like summaries of many studies put together, and therefore create the “average” results amongst all the studies being examined as well as decreasing bias.