When I was on a lower dose of Seroquel (100 mg), it would knock me out. You definitely feel it coming on....and if you are prescribed it, don't make any plans right after you take it! For some reason, Seroquel seems to be less sedating at higher doses due to it acting more like an antihistamine at lower doses. However, it does make me sleepy at any dose. No other drug has really helped much with sleep, besides sometimes Klonopin and on occasion Xanax, but barely. Xanax does not last long enough to keep me asleep unless I take a high dose. Other than these meds, I never found any others that helped me sleep. I've always struggled with insomnia, but the Seroquel has helped the most.