You said that you've been taking Z3 for 3 weeks and you are having a hard time sleeping. How pills are you taking per day and how late. If you are taking them in the later afternoon, early evening you can forget about going to sleep. T
hat happened to me once and it was one too many times.
Are you doing any type of exercise or moderated your diet in any kind way?
If not you should. Remember these are not miracle pills. Pills help those who help themselves... Good Luck