My doc gave me a protocol, I think to try and address my Krebs cycle etc, and in that protocol is L-Argenine in the AM and L-Lysine in the PM. Its supposed to influence GABA receptors in the gut and promote more serotonin. All the stuff on L-Lysine I read is that it makes you less anxious. Well, it seems to have the opposite affect on me: it makes more more uptight. If I take it like 8pm or so, I can not sleep until 11pm or later. Anyone else have this issue with L-Lysine? (I seem to tolerate L-Argenine well).