I have the same concerns and every doctor I ask tells me the study show no long term effects at all. One explanation: I tend to take melatonin when I am very t

I have the same concerns and every doctor I ask tells me the study show no long term effects at all. One explanation: I tend to take melatonin when I am very tired and didn't get enough sleep the previous night. But on those nights I sleep very well anyway. And once I have enough sleep I don't sleep as deeply the next night. Perhaps that is a lurking variable for me. Do you have a fitbit or something to track the sleep?