Lying on a bed and holding the book above your head so that the book faces down and you face up towards the book is not always the good position to read. It could damage your eyes, and give you a pain in your neck and hands. Sitting in a couch with your head dropped down looking at your lap might also not be a good idea, since it will cause your neck to ache. So? Always sit your ass on a chair before a desk with a table lamp, lean well on the chair, raise the book to a perpendicular angle to your eyes, and then read.