If i take melatonin for insomnia every night, will my pineal gland stop functioning normally? i do not want to be dependent on an external synthetic drug for the rest of my life?

Taking too much melatonin can suppress your pineal gland's activity, causing rebound insomnia — either rendering the supplement ineffective or worse, exacerbating your already sleepless nights further. You only need tiny doses of melatonin to support your natural sleep cycle. In other words, take the recommended dose of melatonin only -- don't overdo it.