Going from 450 mg to 300 mg is a rather large decrease to my psychiatrist's point of view. Mine usually lowers my dose by 50 mg at a time, though I take Seroquel XR, whose lowest dose is 50 mg.

I hope you feel better at your lower dose. I have been taking 450 mg Seroquel XR for a while now and do great. I never need a nap, and sleep about 7-8 hours per night and wake up fine. It goes to show that the reactions to different doses and regular Seroquel vs. Seroquel XR can vary by person. If I've been manic, even 600 mg (along with my other bipolar meds) only slows me down a little. However, over time higher doses sedate me too much, too, and my dosage is lowered, but usually only 50 mg at a time.

I think 450 mg Seroquel XR happens to be my personal sweet spot, but I tend to be able to handle higher doses than some other people. I take a rather high dose of Tegretol XR (carbamazepine ER), too, at 1400 mg per day.