It's hard to quantify that, since this is all so subjective and I don't really put a lot of effort into trying to make my observations about it rigorous / scien

It's hard to quantify that, since this is all so subjective and I don't really put a lot of effort into trying to make my observations about it rigorous / scientific. But my subjective perception is that it does help me focus and function a bit better. The combination of caffeine and L-Theanine, along with 5-HTP on occasion, usually seems to correlate with periods when I'm very productive. But, again, this is all pretty subjective. And even if there is a positive effect, it could just be placebo effect for all I know.