I have had Reynards syndrome for most of my life my sister also has it. I believe for most of us is an auto immune disease or syndrome. I find I get it when my body is cold inside. Try to keep as warm as you can! It could be 95° outside and then my supermarket keeps freezing cold and my hands get frozen. Trying to keep as warm as you can is your best bet it’s not always easy! I can remember being in a cold position for quite a long time and it took hours for my numb fingers to heal up. I really got nervous I really didn’t know what was gonna happen with my fingers so I got super cold inside and that really was not good! I only helpful hint is try to keep your body warm inside and outside so it doesn’t give that feeling that some of numbness! it certainly can’t hurt to try to keep as warm as you can!