Hi InstantLunch, I'm not sure if hormones are your problem. Hormones essentially control every action your body makes including the physical aspects needed for playing saxophone, but I wouldn't pin this as the problem. If you are a female the chances of a hormonal imbalance at certain times of the month may arise. Also if you are going through puberty then it may be possible. Still i'm not completely sure that the physical hormones are affected by those reasons. There are also people who suffer from hormonal imbalance. This can result in depression and many other serious perblems. I would probably bet that your problem is completely mental or instrument related. You can't expect to play a song you have practiced perfectly to be 100% perfect every time you play it now. If you performed the piece then your nerves and many other mental factors come into play. Also your mood greatly effects wether or not you have a good playing session. Events that happen throughout your day can subconsciously change the way you play something. The instrument may be a factor as well, or more likely the reed. If you've switched reeds lately then a bad reed might affect your sound and take getting used to. All reeds are different. Also, reed placement, reed wetness, and ligature placement can hurt your playing from session to session. If you are a newer player the problem might be found in your embochure. New players struggle constantly to find the right mouth position and even the slightest unnoticed change from note to note can affect your playing which in turn may make you frusterated and tense causing you to miss notes. I'm sure many other saxophonists have this problem too as I do from time to time, but no matter what I try to never pin the problem on one specific thing. If my fingers and body don't want to work I don't just say, "oh, it must be the reed." I usually step away from the fusic and take a few deep breaths to calm myself down. I know that usually my problems are just in my head.