https://www.projectmonkeymind.com/2018/01/benefits-loving-kindness-meditation/
"Increased Dopamine
Feelings of compassion towards others have also been shown to activate dopamine, which is a powerful neurotransmitter that works to calm our nervous systems and increase our energy. Dopamine is also known as the ârewardâ chemical, which means every time you practice LKM youâre receiving a positive reinforcement."
The above statement is derived from research article at: https://www.ncbi.nlm.nih.gov/pubmed/19428038
Neuropsychologia. 2009 Aug;47(10):2073-81. doi: 10.1016/j.neuropsychologia.2009.03.017. Epub 2009 Apr 5. Compassionate attitude towards others' suffering activates the mesolimbic neural system. Kim JW1, Kim SE, Kim JJ, Jeong B, Park CH, Son AR, Song JE, Ki SW." Hope this helps