I am currently breastfeeding my 18 month old son, is it safe for me to take 5mg of melatonin at night?

Ask your OB: I see you are taking thyroid medication and still breastfeeding. Although melatonin is generally considered safe, you want to minimize medications that can be passed to the baby from breast milk. I would call your OB's office and ask to speak to the nurse, who may then give you the doctor's recommendation, especially if you don't have time for an appointment.

Probably but...: There is no evidence taking melatonin is harmful when breastfeeding, but little evidence it's safe; research on this hasn't been done. But melatonin is a natural hormone that's very safe & normally secreted in breastmilk. Melatonin is likely to be as safe or safer than any other sleep aid you can take. Here's an interesting article speculating melatonin may help newborns:http://tinyurl.com/ndtt2ce