This is very true for some types of books. For example, I am not able to read Dostoyevsky or Carlyle fast. For some sort of books, I even feel like I need a nap

This is very true for some types of books. For example, I am not able to read Dostoyevsky or Carlyle fast. For some sort of books, I even feel like I need a nap after 30 mins of reading, as I feel that my brain gets tired :)