PRL and metabolic disease: Finally, inasmuch as the circadian rhythm of plasma prolactin has marked influences upon immune function [141], and bromocriptine is a strong inhibitor of pituitary prolactin secretion, the appropriate circadian administration time of bromocriptine to treat metabolic disease must also take into account the functions of circadian plasma prolactin upon immunity (and several of its other functions—e.g., in reproductive physiology) so as not to disrupt them.