i have never had restless arms, but what helps my restless legs is
1. no alcohol
2. no antihistamines
3. do not sleep on back, but if it is necessary, elevate the head. i have a wedge i used when i broke my shoulder. some people use recliners.
4. no antidepressants. they don't work if they deprive u of sleep anyway
5. hug on the dog

i have heard that synthetic fabrics cause it too, so you could try cotton pjs and sheets.