I have just changed from fluoxetine prescribed for depression to mirtazapine. The fluoxetine helped but gave me terrible insomnia so my doc changed my presription to mitazapine which i have only been taking for a week. I feel terrible, like a total zombie. I just want to sleep all the time & my brain is in a total muddle. Is this normal? I dont know what to do if i should keep taking it or not. Please help