If you've been drinking alcohol, it's also not safe to take melatonin. natrol Melatonin is also not for you if you're pregnant or breastfeeding. Researchers simply don't have enough data to know if it's safe for fetuses or breastfed babies. The common negative effect is drowsiness, so it is not to take Natrol Melatonin before driving or operating heavy machinery.
https://www.cprarticles.com/category/health/44868-what-is-natrol-melatonin