Gradually, the opioid receptors in the brain become less sensitive to the drugs, so the body demands higher and higher doses to get the same feel - good benefit. (sciencenews.org)
«There are receptors in the brain for melatonin that regulate brain chemicals related to anxiety and calming,» he explains. (nyparenting.com)
Yet, we know that sugar stimulates dopamine receptors in the brain involved with reward. (cathe.com)