I sleep on my back only because of my CPAP machine and it does feel amazing! But I'm really a side sleeper and it hurts my shoulder after a while so I toss and turn. I still get REM sleep but I usually just end up back on my back with this. With my original purple mattress I could sleep on my side no problems. This stays or feels cooler through out the night than the purple mattress.

Still in my 100 night triple, bought 3 weeks ago, and I'm not 100% sold on it yet. Time will tell.