I love theanine as a low-level anxiolytic. My recommendation:
* Try a lower dosage first. 400mg made me irritable. 100mg works great for me.
* Effect seems to lessen if taken consecutive days; in fact it might have the opposite effect of making one more irritable than calmer.
A few nights ago I was tossing and turning because I had too much coffee before bed. A theanine pill and sleep was restored. It doesn't do much more than that, but it's good to have for one of those days that you just want to punch a wall.