I can sleep on my back or on either side. I can’t imagine sleeping on my stomach; I would need to turn my head 90° to the side to breathe, which would leave my neck in an extremely uncomfortable position. Why don’t other people have this problem?
I prefer to sleep on my stomach but can occasionally fall asleep on my left side (until my left arm starts to tingle) and on rare occasions on my back. Never on the right side.
I thought this was going to be a which side of the bed do you sleep on thread…
Kjckjc… we have that same voice in my house too! Except he never hears it 
I have a television with an automatic timer in the bedroom, so quite often the last position I remember is on my back.
However, when the tv is off I sleep on my left side if I want to think of something new before falling asleep, and on my right side when I want to solve something before nodding off. I know this makes no sense, but somehow it works for me.
Any side is fine with me except for tummy. I love tummy sleeping but my shoulders get stiff. The weird thing is I have to start off on my back, get sleepy, then move to one side or another to fall asleep. Then I curl up tight like an armadillo.
Also, the head of the bed must always be on the right (if you’re standing at the right side of it). My whole life I’ve never been able to sleep with it any other way.
in a fetal position in the remaining 2’ triangle of space left by Mr. Maureen.
I used to be like pipper and insomnia4AM. But after my brain surgery I cannot sleep on my left side (the surgery side) without getting a massive headache so now it’s the right side for me.
Next to the wall, it happens to be the left side of the bed (looking at your feet as you lie in it). Irishfella needs to stretch, I just end up being rolled halfway up the wall, with one of his arms draped around me.
It’s kind of cosy.
In a bed I like to sleep on the LEFT SIDE of the bed (left judging from when you lay down not when just looking at the bed). And I need to lay on my right side and then right before I fall asleep I switch to my left and it’s off to dream land. I can sleep on my back, but I rarely do. When I’m on my side (either) I am usually half on my stomach too.
Before I got my reflux under control, I slept on my left side a lot. Nowadays, I mostly sleep on my right side. For some reason, if I sleep on my left side, my head gets stopped up and I end up breathing through my mouth. Nothing worse than waking up with a dried-out open mouth in the middle of the night or in the morning. Yuck.
I like to sleep on my back, but can’t always manage to do that. Sometimes my back or legs ache too much for it. When I do sleep on my back, lots of times I wake up with my arms over my head.
My S.O. sleeps on his stomach a lot. I can’t sleep that way at all.
I alternate between both sides. Occasionally on my back. I can lay on my stomach to read, but never to sleep.
When I was twelve, I had some surgery done that required me to sleep left side up. My mum decided putting my hair in a pony tail and tying a rope from my pony-tail to the bed foot was the best way to accomplish that. Funnily enough, the next surgery happened when I was 16, and I bought myself a bean bag, which did the job much more comfortably, without hair pain, restricted movement and avoided all the tied-down can’t-move fire-raging nightmares I’d had the previous time. These enforced periods of sleeping a certain way ingrained in me my sleeping on my right side.
I’m slowing starting to try sleeping in other positions, and have a position halfway between sleeping on my side and on my stomach that is pleasing. 
I can (and do) go to sleep in any position. Usually, I go to sleep on my right side holding on my full length body pillow. In the middle of the night, I roll onto my left side and hold on to my wife.