I have generalised anxiety disorder with post natal depression and anxiety

I was hospitalised but thankfully feeling alot better but my anxiety is still an issue

I am on lexapro 30mg and was on seroquel 25mg and would cut in quaters to get me through the day

My psychiatrists suggested i go on serequel XR 50

I take at night around 6pm but the next day im so tired

My question is how long intill my body gets use to this drug and i wont be tired? And when will it help my anxiety?

Ive had to resort back to clonazepam when i really can not cope.