L-theanine works for me, although info take it at a pretty high dosage (3x350mg), which I take twice, once in the morning when I get up which gets me through the workday, and then the same about 2 hours before I go to bed. The effect is fairly subtle, since it doesn’t have the obvious sedating effect or a benzo, but it seems to do something for me, at least, to take the edge off.

I’ve been on this regime for about 2 years now, and haven’t noticed any sort of tolerance build up.