We bought the full mattress for our 4 year old. I would say it is more of a back or stomach sleeper type and not so much for a side sleeper. At least when I slept on it, my hip was not comfortable when trying to sleep on my side. It is great for kids though because I doubt they have too many complaints about any sort of body pains! My daughter hasn’t complained at least. We bought this without a box spring and it works just fine. The mattress is of good quality and was expanded by the next day.