My wife and I purchased
My wife and I purchased a memory foam mattress that included a "free" mattress protector. The one included was billed as waterproof, but was very plasticy (?) and retained a ton of body heat. I found the Slumber Cloud Dryline protector, and long story short, we love it. Having slept on the Dryline since last summer, I live in the Midwest, and have used it in both humid summer nights and cold winter nights. I sleep much better with the Dryline protector. It was noticeable the first night last summer how it transferred the heat away from my body without making me feel sweaty. I would definitely recommend to anyone looking for some way to help with sleeping hot.