Although I have been on Seroquel 400 XR for many years, my memory started to get really bad over the last 2 years. I don't think Seroquel caused this level of memory loss, but there is a good chance it is contributing to it. Normally I need 8 - 9 hours of sleep. After going down on Seroquel by 25mg for 4 days I needed 12+ hours of sleep. When I wake up I take 400 mg of Provigil and am ok for several hours. 2 days ago I only got 9 hours of sleep and 400 mg of Provigil did nothing. Last night I got less sleep and am not tired, but I have Bipolar Disorder and i get a very mild type of hypomania where I don't get enough sleep and am not tired for several days in a row. Over the next week I'll see if reducing by 25 is still causing such severe sedation.