I was a bit worried about that but was pleasantly surprised at how mild the sides of Tren E were. I started low and tapered up, was careful not to dose too much test. I have had trouble sleeping once in a while but only for a day or so during the week. I love the stuff. With the gains, no wonder its everyones favorite.I always recommend ace for first time Tren users just because if the sides get bad, you can back out and get it to clear quick. After that, I'm all about long Ester. I only use Tren e now