depression
"Starting a new college last year I became very depressed, strongly related to a sudden onset of chronic insomnia since I couldn't sleep in my new bed at school. I took mirtazapine to alleviate both conditions. It definitely helped my insomnia initially, but then its sedating effects wore off within weeks. It probably made me less depressed because I didn't have as much insomnia, but it also certainly made me emotionally numb and extremely groggy for the past few months. 
I regret taking it for more than a couple weeks. This should be a SHORT term drug for insomnia, not a long term drug for depression. Tapering off after only 4 months on 30mg has been very difficult; 3 months later I'm now on 2mg and getting off it in a week. SHORT TERM ONLY"