400mg of fast release would knock me out for 12 hours, and quickly. It is also an extremely high fast release dose. Most people take 25 -200mg. I was on 300mg of fast release Seroqual a few years ago. I took it half an hour before I wanted to be asleep as if I took it earlier I found being able to so simple things like brushing my teeth, or walking up a few stairs to my bed, impossible as I was so out of it. I soon went off Seroquel as it gave me restless legs and wasn't helping me anyway.