Judy, and all, That's interesting about the study. I currently take my .5 of Dex at or around 11:00 (usually 10:00 weeknights) and I have always wondered what would be the optimum time. My prescription just says .5 at bedtime (I take .125 when I get up too). I have noticed that my body can tell when it's close to 11:00. I start feeling bad. Do you have any further info? Susan A.