Melatonin’s sleep-promoting action works as a step function, meaning that if you get enough of it, more won’t help (and could be harmful). Although over-the-counter products commonly available often contain 5–10 mg (and at least one manufacturer sells 60 mg tablets), overdosing can cause extreme drowsiness the next day and disrupt your sleep cycle for a week or more.
over the counter melatonin can be detrimental as it can overdose you causing you to feel groggy.
