Is Numbness Throughout My Left Arm Upon Waking Up A Serious Concern?

When I woke up this morning from the top of my left down to the tips of my fingers, I couldn t feel my arm. it would not move no matter how hard I tried to move my arm. with my right arm, I picked up my left are and starting rubbing it. I tried hard to move my hand and slowly I wiggled the tip of my fingers. I kept rubbing my arm for a while and slowly I started feeling it. now I can move my arm but It feels very weak and my skin feels tingly. what can this be..?