Then I alternate between left and right side about every 90 minutes. The days of sleeping for hours at a time are gone I'm afraid.

is that like sleep walking??

during the night. For example, I chose "back" because that is my default position. But during the night I also sleep on my right side and my left side. Never on my stomach.

I broke my right shoulder in '22, so that side can get sore, but I do flip flops. I also sleep like a flamingo, with one leg bent at the knee and the other straight.,

gives el gato 10

to find a comfortable position for shoulder/upper arm lying on the opposite side.

So, I've had to learn to sleep mostly on my back but leaning into my left side. (a special pillow helps).

I empathize with all who struggle to find a comfortable position to sleep. It can be miserable. The best advice I have is to not go to sleep with active pain. You'll never fall asleep. Slather your topical meds (Aspercreme and the like) and take any NSAIDs --if you can-- so that you get some pain relief overnight.

... but I move periodically: left side, right side, and belly - not usually on my back.

Very rare, briefly on stomach now. Too fat in that area (not super fat, but enough to not stay too comfortable for long). Each night I'll feel more comfortable this way, or that way, sometimes changing within a night.

I empathize w you posters and shoulder issues. I was lucky, left shoulder ripped rotator muscles (a freak accident), and resultant bone scar affected my ability to use certain drawing techniques, and ruined the new style I crafted over several years;
but not daily activities in general, otherwise. If I'd been a gymnast, that's have been different! Luckily, didn’t affect sleeping on that side. At least if it had, I still had 2 comfortable positions to choose from.

A toast to better, and good sleep, DU'rs!

On my left side but at a 45 degree angle toward my back assisted by pillows. That's it, after a few hours I have to get up for a couple hours and then go back to bed for another three or four hours. If I manage to get into another position I wake up with nasty pain in my neck, shoulder or back. Sometimes it makes me puke.

I know I change positions when I sleep but when I fall asleep I'm on my back and when I wake up I'm on my back.

right-handers outnumber left-handers, but more DUers are left-side sleepers than right-side sleepers? Is it because they want to keep their dominant hand/arm free for fiddling around?

Tiny Tim did!

anatomically speaking.