It could be that you aren't in the right environment for you to learn best. Some people work best at night, some in the morning. Some learn better when they can write it out with a pen and paper and some work better typing. I think it's all about figuring out what helps you learn best.

If the problem is with focusing on reading a textbook, I have the same problem. I suggest trying to see if you can get an audio version of the information. Or if it's on a common topic, see if you can find a video about it and watch that. If all else fails, break it up into little chunks. Read one section at a time and then try to summarize what you just read in 1-2 sentences. It really forces you to condense the info and pull out the most important parts. The more interactive you make it, the easier it will be to stay engaged.