Have you ever had the experience of not being able to maintain concentration while reading and/or not remembering what you just read? Of course, this can be from a number of causes (e.g., boring or extremely dense reading material, ADHD, a mild reading disability) but an obvious but often overlooked one is not getting enough sleep. When I try reading late at night or when I’m clearly sleep-deprived, I can only read for a few minutes before my eyes grow heavy and my attention drifts. I keep rereading the same passage because I just cannot maintain my concentration. Retaining much of anything seems next to impossible. On the other hand, when I’m well-rested, I can easily read for over an hour at a time and I find my retention to be much better.
So, if you’ve noticed that you have a lot of difficulties with reading (and have not consistently experienced these difficulties throughout your life), be sure that you are getting enough sleep. Really aim to get around 8 hours of sleep per night. If you just want to try this as an experiment, that’s a great way to do it. See if reading becomes more of a pleasure than a chore when you’ve been having the proper amount of sleep.