<p>After administration, melatonin binds with its receptors. Two types of melatonin receptor subtypes - MT1 &amp; MT2 have been identified in humans. Melatonin receptors are found in the brain and some peripheral organs. The MT1 subtype is present in the pars tuberalis of the pituitary gland and the suprachiasmatic nuclei of the hypothalamus. The MT2 subtype is mainly present in the retina. Increased level of Melatonin initiates neural &amp; endocrine signals to optimize the levels of neurotransmitters e.g. increased serotonin, increased GABA &amp; decreased dopamine, which induces &amp; sustains sleep, as well as, maintains the body&#39;s circadian rhythm.</p>