This Thing’s Incredible A series where we share products that are so good we would do an entire infomercial about it. (But instead, we published this review.) Read more here . Photo: Hilary Reid My sauna-blanket obsession started out as a joke. It’s hard to explain without eliciting confusion or eye rolls — which I admit is how I used to think about it. I first heard about the sauna blanket when a friend of mine tried one belonging to a friend of hers. “It was so relaxing I fell asleep,” she