What Happens to Your Body if You Take Melatonin Every Night, According to a Behavioral Sleep Medicine Expert

“One of the challenges with melatonin is that recent studies have shown that the dose on the bottle may not always equate to exactly how much is in each pill,” Dr. Conroy says. "A lower dose of melatonin has been shown to show a bigger 'shift' in the circadian phase than larger doses of melatonin."