Melatonin is currently the most popular and well respected of the natural sleeping aids available
. It is a more direct precursor to serotonin than is tryptophan. Melatonin is also much cheaper. I almost always will recommend melatonin to my clients as the first thing to try to resolve sleep problems naturally. But one thing I have found is that for some reason the people that do not respond well to melatonin can sometimes find it effective. For many people it is a useful natural sleep aid, but tryptophan has never really regained the popularity that it once enjoyed prior to 1990.