I started getting anxious. I tried to deny it. Then severe anxiety and insomnia set in. I had been using this stuff for about a year and always have had a certain irritability after workouts. It progressively got worse until it got my attention. BIG TIME! I've always steered clear of uppers and andro, tribulus, ephedra and similar supplements. So it seems that I can, with a lot of confidence, narrow my acute neurotic spell to creatine. What further contributes to my opinion is that the symptoms vanished after stopping. It was almost immediate, but it did take about a week to feel normal again. At this point, as good as it was to be making huge gains--steroid-like gains--I felt it wasn't worth it at all. Being in that hell dimension brought things into perspective. I just wanted my mental sanity back. To be fair, one could say I went nuts and that there is no link to creatine. Personally, it seems highly unlikely.