I’m a lousy sleeper. I’ve always been a lousy sleeper. I woke up a few nights ago in the middle of the night and grabbed my phone and looked up sleeping. And I saw Mayo Clinic talking about having a pillow between your knees to keep your back straight. I shrugged. Put a pillow between my knees. And I was like, “holy shit, this is comfortable.” And I didn’t move for like 2 hours.
I’m a tall guy and I got long legs. And presumably, wide hips. So it’s not entirely comfortable to have my legs exactly parallel and on top of each other while I sleep. But if they aren’t aligned if you’re on your side, then your back will twist.
I’ve now done a few nights with a pillow and it was very comfy and a great sleep. If you sleep on your back, they recommended a very small pillow, like a rolled-up towel, under your lumbar. I tried that as well, but it was a bit harder to find the right size.
https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&ContentID=4460