see things
see things  {v. phr.},  {informal}
To imagine sights which are not real; think you see what is not there. 
I had not seen him for twenty years and when we met on the street I thought I was seeing things.
She woke her husband to tell him she had seen a face at the window, but he told her she was seeing things.
Categories: 
 
Source: A Dictionary of American Idioms

