I use now tryptofan and it helps me a lot, the best i've ever tried on the natural front.
I use "amino1500" from the brand NOW (don't know if you can get it in your country) 5 tablets a day and it does wonders !!!!!!!!!!!!!!!!!!!
The tryptofaan is mixed with other amino acids so I don't know if only tryptofaan is justy as good as this one is.