You can test a pillow for five minutes. You can squeeze it, press your hand into it, lie down on it, and decide whether it feels comfortable. But there is one problem. You don't sleep for five minutes. You sleep for hours. And during those hours, your pillow is doing something very different from what it does while you're standing in a bedroom looking at it. Your head moves. Your shoulders shift. You change positions. The pillow compresses and recovers. Your bedroom temperatu