I have these or something similar. I call them tremors, but they couldn't catch them in a sleep study. I usually get them in my legs, but I also get them in my chest, which is very bothersome. They are very fast muscle spasms. When they are in my chest it feels like my heart is racing, but my pulse is usually normal. The muscles in my chest are racing, lol. I usually take magnesium and it seems to help. When they were really bad I took norflex and they completely stopped. They do come back, but the norflex worked. It's a muscle relaxer used for Parkinsons. I no longer take the norflex as I woke up 1 morning and felt like I was jumping out of my skin. Give the magnesium a try. It does seem to calm them down. I wish I could try other things, but I am scared of medication and supplements now.