The most helpful one is making the top of your tongue meet the roof of your mouth and pulling it backward as far as you are able. Simultaneously move your jaw down forcing it as much down as possible slowly, while not losing roof-tongue contact.

Hold the stretch, repeat the same for a couple of minutes and your muscles will ache. This also unclogs your sinus, so don't be surprised if you need to swallow or clear your nose. Also, don't do the full stretch at the first try. Warm up a bit first.

There are several others, but take too much time to describe here. You can research online. This is not obscure information. My doctor gave me a writeup. Please note they take a few days to take effect. Personally, I found them effective within a week, but YMMV.

Singing also helps - less effective but more fun (well, for you, if not others who will wince).

I am interested in researching it online, but what search terms should I use? I've never heard of this before. Thank you.

sleep apnea exercises. Additionally, sinus clear exercises will help if your nose is blocked.

https://www.sleepfoundation.org/articles/mouth-exercises-to-... https://www.cpap.com/blog/exercises-alleviate-sleep-apnea/ https://www.southfloridasinusandallergy.com/14-convenient-ex...