Hi all, im new here and have suffered from anxiety attacks for 15 years..I have been on Celexa 30 mg and Xanax for about 8 years..My question, I have been going thur some sleepless nights which i think and my Dr thinks is anxiety related..He has upped my celexa to 40 mgs and i was wondering, when u up a dose, how long does it take to get in your system, even if you already have it in you ? thanks guys.