Every night I have undetected heavy sleep

Can anyone explain why this is happening every night and how to prevent it? I have the phone on a little bedside table right near my head, and short of putting the phone under my pillow I don't know what to do. Even now I don't feel fully comfortable with the phone so close to my head just in case O_O

What does everyone do for this/where do you place your phones? Are the pokemon Go things better?