Are you a right-handed person? You probably move that hand around more, have a little bit more circulation because of that, and that may explain the difference in temperature. If it's winter where you are and generally colder in your home that may make you notice it more because a body part that moves less is going to be colder, especially a hand or foot.
I'm left-handed, which makes this even weirder. I definitely move my left hand/arm more than my right. Yet, when I sleep on my left side, my whole left arm will often "fall asleep" (it gets numb and hard to move, and then all tingly), but this never happens to my right arm.
Have you tried magnesium supplements?
I'll try this! Where do you get the fizzy drink?