Disturbed sleep / inability to settle / anxiety can have physical causes although these are poorly recognized / diagnosed by regular allopathic medicine where I live.

Anecdata: 1) A good friend whose anxiety was largely alleviated (and sleep improved) by recognizing and treating their iron deficiency. 2) I have to (can't take the Western drug which was prescribed any more, and the Western doctors can't seem to bang the rocks together) take herbs for my hypertension but as opposed to the side effects I was experiencing from the drug I joke that all of the "side effects" from the herbs are good, they're targeting imbalances which were not recognized / treated previously and lo and behold I settle and sleep better... which helps reduce the blood pressure.

I spoke about it in this video: https://www.youtube.com/watch?v=QnNPRqLVtaM

Primary, idiopathic insomnia doesn't really exist. It's almost always anxiety, although a few other mental and physical conditions can also cause it. But more likely anxiety.