This is a very hard mattress. I'm Asian who grew up sleeping on hard beds and always preferred harder beds, but this one hurt my shoulder. I've slept on this mattress for 4 months now. About a month or 2 ago my right shoulder started to hurt even during the day. I just played pool last week and I can't rotate my right arm backwards without feeling pain. I always wake up sore and tired now when I wake up on my sides. I can only sleep on my back flat on this mattress otherwise I wake up in pain in my shoulders and back.