I took the advice of the mom who said her 3 year old would sleep an entire night on this mattress. My 3 year old has not slept a full night on this mattress once yet, and I found out why last night when I fell asleep on it next to him. I woke up in the middle of the night with my whole body in pain. I escaped to my own medium firm queen mattress in my room and felt immediate relief. This is not a medium firm mattress. It has very little give. I would rate it as a fully firm mattress. The one benefit is that it is reversible.