i'm pretty well versed on sleep aids. besides ambien, i've found that zinc (that's right, cheap old zinc in 50 mg doses) helps me sleep better than valerian root, melatonin, nyquil, etc.
I don't think it was illegal....it was just largely discouraged by the FDA because some poorly made l-tryptophan caused people to develop something called EMS or MES SME or something like that. I think its basically like ephedra is right now....its not illegal, but companies shy away from making it beause of perceived risks.
No, I'm pretty sure the FDA has taken trytophan off the market. Not saying it was a good decision but it is not supposed to be sold in the U.S. as a single, free-form amino. Blame the Japanese. It was a company over in Japan that cut corners and ended up killing people.
The FDA has taken trytophan off the market because the drug companies would rather sell their much more expensive antidepressants and sleeping pills instead (even though those drugs are no more effective and may have strong adverse side effects