I sleep sort of diagonally, it's not on my side but not exactly on my belly because I have a pillow wedged underneath me. It helps because when you're on your belly your neck needs to turn a lot to be sideways which is awkward so this relieves some strain. I also have an autistic setup of a series of other pillows at strategic positions to support my limbs and joints because not having them there makes it hard fur me to sleep unless I am extremely tired. I currently use 6 pillow in different spots and with a few folded blankets as well fur extra support. I think sleeping with another person would be uncomfurtable because my joints wouldn't be at the right angles