I just want to caution those who have never taken L-Theanine before. Many people have experienced greater anxiety than they were experiencing before. Sadly ironic, most of them were seeking something to relieve their acute anxiety and high blood pressure. I had taken it to relieve my high BP and at first it was amazing. I was so alert and calm at the same time. I checked my BP with my home unit and it was indeed much lower. I let the dose I took wear off and I was subjected to heart palpitations and anxiety big time. It was as though there was some sort of "snap-back" effect where the symptoms were suppressed but once released came back amplified. If you wish to read over 150 personal reviews (both good and bad) try this website.
https://www.drugs.com/comments/l-theanine/
Good luck. I hope you find relief to your problems.