I spend about 6 hours a day drawing in front of a computer and 1 or 2 hours playing video games. I tend to forget to take a break, so yes, I got the occasional back ache, and my eyesight dropped a bit. Haven't experienced pains on wrist or neck or any other parts though.
Most of my day is spent in front of a computer. I don't get any aches nor wrist pains myself because I sort of got used to working in a way that avoids their cause.
To avoid problems I'd recommend not working on the same piece more than 2 hours, switch up, do other things, let your eyes adjust. It also helps to set the screen brightness about halfway down the scale - a bit higher than what reading lighting should be. For the wrists, exercise and stretch. Same as an athlete needing warmups, the artists needs to control his tool - his main hand - well. Also, set the tablet sensitivity lower, so that barely touching gives you solid lines, and you don't need to press hard to get a result.
I work for nine hours a day in front of the computer at work and sometimes several more hours an evening.
I used to get wrist pain and eye strain. I set up my desk differently and got a wrist pad and that helped with my wrist. I actually had to start sleeping differently as well, because I was sleeping with my wrists curled in at night and it was aggravating the inflammation. For the eye strain I moved my monitors farther away from my seat and it has helped immensely. I also try to get away from my desk each hour.
When I am doing digital work I work at minimum screenlight or really low. Depending on the computer. I spend some hours when drawing, from 4 hours to some days. As for health problems. I get tired sometimes. I do have wrist pain caused by bad position of hand while drawing.
I've been working with computers for 12+ hours a day for years, and my eyes are no worse than they ever were. And the only blind computer programmer I know started out that way. On the other back and wrist pain is pretty much constant. Take a break at least once an hour to stretch your back, neck and hands.
Eye exhaustion and neck aches are normal when doing digital or traditional art. I normally work on a piece for about 10-1 hours at a time and less if Em busy that day or too lazy to work on it. Only advice I have s tilt you head to the side for 20 seconds and then do the same with the other side, sit further away from the screen and if you were glasses try and get ultraclear for them as that helps reduce headaches and stuff. Also take a 10 minutes break every hour.