I've been on and off Temazapan for a couple of months now. I used to just take 1. The doctor said to take 3 at a time, so 30mg. I'm trying other things now. Advice I've been given includes:

Bed is for sleep only (there's also another use but not relevant here). No TV, no reading, no computers, no iphones etc. Lie in bed. If you dont get to sleep in 30min, get up and walk around the house, lights off. Go back to bed. Repeat.

Warm milk with a teaspoon of honey. Take 30min before bed.

Turn off any stimulating activities 30min-1hour before bed. This includes TV, computers etc. Low lights (I turn on lamps instead of overhead lights), put some soothing music on, follow a going to bed routine.

Exercise in the morning helps improve sleep

Check Vit d, zinc and magnesium levels are ok. These can affect the body clock.

Turn off wi-fi. Turn off mobile phones at night. EMFs can affect brainwaves.

If he has ADD or something similar, he will find it difficult to turn his head off at night. Non-adders can be affected by this too. Writing in a journal before bed to get it all out can calm the brain.

Hope some of these help. I find them hit and miss depending on what I'm dealing with and how strict I am with winding down routine. I seem to be addicted to my iphone which keeps me awake. And sometimes I'll
do everything right and still not be able to sleep. I'll fall asleep eventually, I'm just a write off the next day.