It is easy to daydream (i.e. space out) when you try to read anything uninteresting, so this often does not bode well for college students who need to read large sections of insipid textbooks as part of a required assignment.
to become distracted or disoriented; to lose attention or focus
Heceleme
to be·come dis·trac·ted or disoriented; to lose at·ten·tion or fo·cus