I've been taking L-theanine for about four days now and I love it! I take the Suntheanine ones, very delicious chewables. Whenever I take it I feel very awake, alert, everything around me seems brighter, I think straighter, don't second guess every thought like I do when I don't take anything. It also makes me a lot happier, although if someone rubs me the wrong way, as they say, I will snap at them with a lot of force but it's more controlled and I feel more confident in what I tell that person. I'm not stumbling on my words and losing control of my temper. The first day I took it I actually wrote (an article for my blog) for 5 HOURS straight and only took a break to eat, it was incredible. I haven't been able to concentrate on anything for a while now. I can also read for longer periods of time without getting distracted. So far I'm really loving the results, I hope they continue this way!