What happens if i overdose on melatonin?

Melatonin can accumulate in the liver if used in high does for a long period of time, several months or more. This can lead to higher than normal melatonin levels in the morning hours when they should be lowest, making it hard to awaken, causing mental fogginess, etc. High melatonin levels can also suppress normal adrenal function, especially in the early morning hours, leading to fatigue and lethargy. Melatonin should be only be used on a short term basis, in small doses (1-3 mg. are generated naturally when healthy) and as needed to correct abnormal sleep patterns, due to stress, jet lag, etc.