My partner and I run extremely hot especially at night and run the AC year round even during winter. I never purchase memory foam due to lack of breathability and hotter sleeping temperatures. Needless to say I was highly skeptical that the Zinus Bliss mattress would be any different. My partner and I slept great all night for the first time in months! My father-in-law house sat for us and said that the bed was perfect for his old bones.   The bed is a perfect medium between soft and firm suitable for back or side sleepers.