Are you taking about Remeron ( generic is Mirtazapine)??
It’s classified as anti depressant in USA but often given to people with insomnia.
Also given to people with digestive disorders like me .
I’m on lowest dose . I take at dinner last 2 months .
I take my Half Ambien 5 mg at bedtime about 9 pm ( sometimes other half 5 mg at first wake up at midnight). I usually can sleep 2 hrs or 3 then wake up . Most times I do have to take other half . Some nights I can’t fall asleep til midnight 🕛 Even on meds . I just toss & turn . I
Def have Chronic Fatigue in day and 7 Gastro illnesses chronic 11 years .