guilherme, it could be a lot of things, maybe ADHD, but maybe something else. It could be lack of sleep. It could be feeling down or depressed. It could having a lot of stress in your life so getting distracted by that. It could also be that you find what you have to read for work extremely boring because it is to you. My therapist said to me one day that he had a diagnosis for me as to what I was suffering that was causing me problems at work. Uh, oh, I wondered what he was going to say. What new problem had he found in me? His diagnosis: "boredom."

It sounds like you don't have this problem reading something that is interesting. For me, with ADHD symptoms, I have trouble focusing on both boring and interesting readings.

If you eliminate the natural suspects like getting enough sleep and being stressed and yet still have the problem, it seems like a visit to your doc can't hurt.

Good luck.