I am ALWAYS hot when I sleep. My husband and I were about to purchase a memory foam mattress, so I panicked when the reviews, and friends, told me they are very HOT...so I hopped right on and added this to my order. Keeps the mattress perfect temperature! and I can't even tell we have a memory foam mattress, which is nice. 

HOWEVER, I noticed on some of the reviews for this product people mentioned it "sounds like a waterproof mattress pad" ha! and that is correct. the top layer of fabric or whatever it is, is VERY loud and quite annoying. Which is why I gave this product a 4. It's about picking your battles. For cooling purposes (very important to me) this works great! throw on a sleep machine and you'll be fine :)