I had terrible sleeping problems: snoring, waking up choking with a dry mouth, very restless, etc. I saw these[1] nasal dilators for $9 on Amazaon and bought them on a whim. It took a couple of weeks to build a habit of sleeping with my mouth closed and breathing through my nose, but once I did, my sleep (and therefore life) improved dramatically. So simple. I wish I would have figured this out ten years earlier. These probably won't work for most people with sleep disorders, but if the issue is sleeping with an open mouth due to restricted nasal passages, I would definitely give these things a try before settling on more elaborate treatment.

Also, as mentioned here and everywhere, alcohol destroys sleep. I've (mostly) stopped drinking for sleep reasons, and drink nothing at all 1.5 hours before bed.

[1] https://www.amazon.com/gp/product/B07DSTZ4KM/ref=ppx_yo_dt_b...