Hi Meg . Xanax XR doesn't have a longer half life, it's just an exteneded release preperation. It releases a certain amount of Xanax slowly over the day so you don't have to take as many pills. I think it only has to be taken every 12 hours. It would certainly be conviednient for someone that has to take Xanax 3 or 4 times per day. It would reduce it to only twice a day.