Nate:

I'm on .5 mg Xanax, but not XR. I know with the regular Xanax you feel the effects within 20-30 minutes. It doesn't need time to build up like say my Prozac did. Although, when I first started taking it I was excessively sleepy and it doesn't make me AS sleepy now, but it's just according to the body chemistry and the tolerance of the person. I have a low tolerance for any tranquilizer or pain medication. It just knocks me for a loop. Some can take it and not be drowsy at all. Just according to the person.

Perhaps talking to your pharmacist or your MD would shed some light on this for you.

Take Care,
K.