Dbol can increase seratonin levels, which could account for the sense of wellbeing, and possibly better sleep for some individuals. I've also met a couple of guys who say they can't sleep if they take their last dbol tab to late in the evening. As BA said, drugs affect people differently. Bear in mind, some of us (myself, The_Evicerator, a good friend of mine I used to train with and probably many others) can screw for hours on tren, and see no loss of libidio on it, and in fact often have a stronger sex drive on a high dose of tren. While many report loss of libidio and/or impotence on it.