I have a bit hunched posture and overextending joints. I was at a massage therapist before Christmas and she actually told me that there are a couple of spots where my spine has "straightened up". Whatever the hell that means. Due to our small apartment, I've been hunching to the corner of the sofa to draw. I can only imagine what this will do to my posture if I keep doing it for longer. So I'm planning to buy a small writing desk for our living room. And maybe consider a small drafting table in the future to lift the paper up.
Don't underestimate the importance of your posture. When you start getting older, it really starts to bring in the pain if you just hunch all the time. I can't straighten up my shoulders completely no matter how much I try. Headaches are no stranger to me either. This was mainly caused by 21 years of computer gaming but I imagine it being the same with drawing. Maybe even worse if you stay hunched all the time.
I have suffered a nasty RSI in my lower back and a sore neck from spending many long hours hunched over my tablet/sketchpad. Guess the best thing to do to avoid these things is to take regular breaks and sit in a better position, preferably in a comfortable chair with back support, not on the floor like I do.
Possibly. Next time you're drawing stop and consider your posture, and try to correct it. I know that when I draw/paint my posture is awful. My back is tense and hunched over, and my neck is twisted. It's a hard habit to break especially when you're all zoned out doing art.
Make sure your workspace is clear and you're not cramped for space in any way while drawing. Make adjustments to your easel/desk etc so that you minimize bending or reaching, and always be mindful of your posture.
Also it always helps to get up, exercise and stretch every four hours at the minimum.