I am on Diazepam remeron (mirtazapine) and zimovane. I take 4mg diazepam 15mg remeron (mirtazapine) and 7.5mg of zimovane at night. Could this cause irritability and nervy in morn?

Absolutely. . Those are powerful medications at not so trivial dosages. Try spacing them apart if possible might make you feel better. Possible medication interactions could be playing a role also. Your doctor should be able to help you figure out a better dosing schedule. .