Surprisingly, one thing that tremendously helped my sleep quality, and several persons around is wim hof breathing.

I used to do it in the morning, and my brother recommanded I'd switch to just before sleep.

The difference is stark in effects, and you fall asleep like a baby even when stressed, using red light, with heat waves, etc...

Given it's free and don't have the side effects of regular melatonin supplement, I would encourage every one to give it at least a one week trial.