I have tried it but wasn't satisfied with the results. I also would not try to suppress thoughts. Just relax, breathe naturally, and allow the thoughts to go where they will. Just don't follow after them. Using a mantra can help, or also focusing lightly on your breathing, or the sensation of being in your body. If you are committed to FILD, then just be more relaxed about it, with a gentler focus. Also, my signature has tips on getting to sleep in a calmer state of mind.