Hey
First up congrats for your son, and to you for supporting him.
Insomnia is well known when you stop taking an Opiate. Some people have a few days, some much longer, the thing to know and focus on is it will definitely come back sooner or later just hang in there.
Some very obvious and simple tips of he hasn’t already. During daylight hours be upright, and walking about. If he can – exercise, longer and harder the better though I suspect he may not feel like that at all. Anything he can do on that front do it – more the better.
You are dead right about meds, it’s just another pitfall. Natural things that can help are Tarte cherry juice, warm milk, almonds. Nothing is guaranteed as we are all different sadly, they did help me though. Also try reading rather than TV or iPads before bed, that did make a difference.
And I know this sounds very hippy dippy, but guided sleep meditation got me through a couple of rough patches too.
I know how hard this is, and it’s a battle, but keep him going, you can get out the other side, I know as I have been there and done it