In broad overview, all the "feel good" hormones increase during and for a time after massage, while all the "stress" hormones decrease.
Influences motor activity (movement), ability to focus attention, and mood in terms of inspiration, intuition, joy, and enthusiasm.
Regulates mood, attention to thoughts, calming. Subdues irritability. Involved in satiety, reduces the sense of cravings and hunger – both for food and sex. Modulates the wake/sleep cycle. Low levels have been implicated in depression, eating disorders, pain disorders, obsessive-compulsive disorders.
*There is a balancing effect between dopamine and serotonin. Massage is believed to influence the optimal ratio of these two chemicals.
All are mood lifters that support satiety and modulate pain.
Functions in pregnancy, delivery, lactation. Also implicated in bonding – couple bonding, parental/infant bonding.
In adults, functions in the process of healing, tissue repair and regeneration. This hormone is most active during sleep.
All are stress hormones implicated in many stress related diseases and disorders, decreased immunity, and sleep disturbances.
Massage seems to regulate these levels. Massage will calm these levels if too high, but also will increase these levels if too low. Thus, massage affects the balalce of the parasympathetic and sympathetic nervous systems.
Bonus: Massage decreases the stress hormone cortisol while increasing the feel good hormones of serotonin and dopamine. This results in decreasing heart rate, decreasing blood pressure, and blocking nervous system pain receptors.
All healing occurs when the body is in parasympathic ("rest and repose") mode. Massage assists in calming the sympathetic ("flight or fight") nervous system and activing the parasympathetic nervous system.
There are primarily three main locations in the United States where research on massage therapy continues: The National Institutes of Health, National Center for Complimentary and Alternative Medicine, and The University of Miami School of Medicine, Touch Research Institute (Tiffany Field, PhD). The preceeding information comes from this research.