Some science behind the scenes

Endomorphin

Endomorphins are two endogenous opioid peptides - Endomorphin-1 and endomorphin-2.  They have the highest known affinity and specificity for the μ-opioid receptor. Both are full agonists at the mu receptor and the delta receptor.  They can be found principally in the hypothalamus, with histaminergic neurons and may regulate sedative and arousal behaviours.