What I learned from a chiropracter is the back sleeping is ideal, with just a little head support, or none at all. I retrained myself to sleep this way at her advice, and the difference it made in how my back felt was amazing. If I sleep on my side ever, I make sure to have support for my neck, in between my knees, and between my arms. Keeping the spine in alignment, the hips even, and not caving the shoulders is key to a healthy back.

I sleep on my back, no pillow, on a carpeted floor. Very restful, deep sleep and I swear my posture has improved because of it. I used to have shoulder pain when I slept on a mattress on my side.

Esther Gokhale of "The Gokhale Method" recommends sleeping on the back or on the side in the correct posture. Details can be found in her book.

Back or side. Side with pillow between knees.

Any position which allows my bulldog to sleep comfortably against me.

This is a great question. There seems to be quite a lot of variation in the positions people prefer to sleep in. For example, I can only fall asleep on my side or my back, but I often wake up on my stomach. I don't like the way my head has to turn almost 90 degrees when lying on my stomach, but it apparently doesn't bother me when I'm unconscious. My father and brother are the opposite: they can only fall asleep on their stomach/side but often wake up on their back.

Someone mentioned Esther Gokhale's excellent book. For back-sleeping she recommends using a pillow but placing both head and shoulders on it, which changes the position of the spine a bit. I've tried it and can't get used to it. I've also tried back-sleeping without a pillow and can't get used to it, at least on a bed. Lying on my back on a carpeted floor, no pillow feels perfect. Which suggests the question: how much are we messing up sleep/posture by sleeping on soft beds?

Regarding side sleeping with a pillow between the legs, how do you maintain this all night? I've tried falling asleep this way, and it feels great. Then I wake up in the middle of the night and the pillow is down at the foot of the bed! Maybe just a matter of training one's unconscious self?

And on that note, the prevailing popular myth seems to be that if you wake up in exactly the same place/position you fell asleep in, that means you had a particularly restful sleep because you didn't move! It's natural for the body to move every couple of hours as you go through the sleep cycle, and I would think periodic movement is important for circulation and avoiding DVTs/blood clots and pressure sores.

I like sleeping on back, but I snore and can even slip into pseudo sleep apnea if I do it, I wake up in the morning feeling tired and lethargic. I thought going paleo and losing 12 kgs would help that but it appears it hasn't. As a kid I slept on my stomach, so that's the best way for me even now. I sleep with my head on the end on the end of the pillow, with my arm under the pillow, keeps my head in a more comfortable position -sounds odd but it works. I can sleep on my side, but I invariably slip onto my back in the night.

When I got on a kick reading about this, there were tons of varying opinions. The majority said side with a pillow between knees is best. Back is ok, and stomach is bad. Side sleeping has always been most comfortable for me. However, from a posture perspective it certainly seems like back sleeping would be the way to go. Less time hunched up/over, and you gotta think if you are on your back gravity is slowly straightening you out! IMO FWIW exc exc.

I still sleep on my side because I can't get used to being on my back, not comfortable for me. I wish I would because my posture could be better.

Hammock -- any position. I'm a side sleeper, and never felt better than when I was sleeping in my hammock -- I still kick myself for breaking down and buying a bed last year, 'cause my companion didn't like the hammock in the house.

I don't know why, but I can't sleep on my back. I just stay there all night if I try.

I wonder why... it's weird.

Depends on your bed as well. If you haven't looked into it yet highly recommend you investigate getting a very good mattress. Most people will spend $10-20k on a car but not a bed which they sleep in for 8-10 hours (hopefully) a day!