I recently have been using a wedge and it makes a difference. My night coughing has been reduced quite a bit. There was a problem with me sliding down to the bottom of the wedge however. I had to constantly hoist myself up. But, one of our group posted a terrific idea that really works, which is to put another pillow on top of the wedge vertically. Another words, the pillow is not horizontal the way you normally sleep on it. Instead, it is vertical and placed right on top of the wedge. This keeps me in the right position for most the night. I might slide down a tiny bit but it has not been a problem.
@aquanimous, I am so glad that it has helped you to place a pillow vertically on the wedge to keep you from sliding!