This memory foam has really saved my back, and my overall health cause your back is everything! Especially since I'm an EMT and lift people all day everyday, my back takes a beating daily, and before I purchased this memory foam, I had a sore, achy back at night, and when I woke up in the morning, I did not feel rested at all, and woke up with a still sore back. Ever since I purchased the foam, my back feels like new in the morning, and I feel refreshed and ready to go. The foam expanded almost fully within the first hour.