http://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/forgiveness/art-20047692
http://www.health.harvard.edu/press_releases/power_of_forgiveness
http://greatergood.berkeley.edu/article/item/the_new_science_of_forgiveness
http://www.cbn.com/cbnnews/healthscience/2015/june/the-deadly-consequences-of-unforgiveness/
“The experience of feeling unforgiven for past transgressions may contribute to depressive symptoms in later life. This paper tests a model in which feeling unforgiven by God and by other people have direct effects on depressive symptoms while self-unforgiveness and rumination mediate this relationship. The sample consisted of 965 men and women aged 67 and older who participated in a national probability sample survey, the Religion, Aging, and Health Survey. Results from a latent variable model indicate that unforgiveness by others has a significant direct effect on depressive symptoms and an indirect effect via self-unforgiveness and rumination. However, rather than having a direct effect on depressive symptoms, unforgiveness by God operates only indirectly through self-unforgiveness and rumination. Similarly, self-unforgiveness has an indirect effect on depressive symptoms through rumination.” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2868276/