Mirtazapine once helped me very much when I was completely stressed out. Doesn't have the addictive effects as benzos, as far as I know.. I was quite listless when starting, nevertheless it helped me get enough sleep and balance again, so I could recover.
As far as I know, lower doses are used for sleep inducing effects, higher doses will make it work as antidepressant and more stimulating, so when I was too turned down /lethargic by the lower dose, I increased it a bit to reverse the sleep inducing effect a little (paradoxically).

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This information is only my personal experience and does not substitute professional medical advice.