Signs that a particular audiobook isn't for you?

When you're listening to the narrator and it's literally putting you to sleep.  When you listen to it, you're half-dozing, when it's not playing, you're wide awake. 


Usually I don't have this problem but I have the physical copy of the book as well.  I really wanted to try it out to see how it compared, though.  i think I'll just switch instead of listening to the audio. =/