Testing, Testing A series where we methodologically and obsessively try new products to tell you if they’re worth it so you don’t have to do all that work yourself. Read more reviews here . Photo: Retailer “Cooling” is one of the most frequently advertised features in sleep products, from mattresses and pillows to toppers and sheets . It makes sense — many sleep experts recommend a slightly chilly environment for optimal sleep, and even anecdotally most people know how impossible it is to sleep