Can melatonin really help me get over jet lag faster? if so, how long before my transatlantic trip do i need to start taking it? thanks so much.

Yes!: Melatonin levels in your body spike at bedtime, and the general advice is to try taking it when you want to fall asleep. Try 1-3 mg at bedtime the first night after you arrive in the new time zone to help induce sleep at what will seem an abnormal time to your body for sleeping. A rule of thumb is that it takes a day for each hour of change in time zone to fully acclimate to your new zone.