When I had it real bad I was prescribed liquid iron… But a sleep specialist should be able to do a sleep study and prescribe whatever is needed…
Sounds retarded but this has helped me for years in combating RLS is to place a pillow, preferably a body pillow (those huge ones) between my knees (parallel to my body). It has done absolute wonders but N=1 (YMMV).
My symptoms are more of the falling into a deeper sleep once asleep. I wake myself out of the light sleep. Sorry, I don’t know the vernacular too well.