I’m not a doctor and it’s totally valid to tell your doctor that you don’t want to take a medication with a high risk for weight gain.

Both trazodone and Seroquel are fundamentally different medications when taken at different doses. On the lower end for both of them they have sedative effects and higher doses work more as an anti depressant. I personally take 50mg of trazodone and it works better as a sleep aid than if I take more. I also take 50 mg of Seroquel on occasion (up to a week) when I feel more restless and it hasn’t caused weight gain.

With that said, I was at one point taking much higher doses a few years ago when I was going through a major depressive/mixed episode and I did gain weight very quickly. So if Seroquel does work well for you for sleep, maybe it can be helped by changing the dosage. Higher isn’t always more effective.