Night blindness

Today, my roommate suddenly stared at me and said, "Sin Yee, you are a pretty girl! " She applied a vague statement. What is the standard of the 'pretty' in her opinion? Why did she say so? 'Pretty' in what way? Internal or external? Well, but in the end she told me that actually she has night blindness, and she can't see very clearly during the night, so she have illusion that I am a pretty girl....