Luckily you never switch on the light

There was two girls who lived in an apartment. One night Annie wanted to go out to a bar and asked her friend Julie if she wanted to go with her but Julie wasn't much of a party person so she said she wanted to stay home and read. So Annie went out to the bar and met a man and they both became drunk and he asked her back to his home. She said that she had to go to her apartment and get her medicine and the man was ok with that. So she dropped by her place and saw the lights off so she didn't want to wake Julie so she didn't turn on the lights, got her medicine and headed out the door. When Annie got home the next day she walked into Julies room to talk to her about her night when she saw her head on the floor and a trail of blood that lead to the kitchen, there she saw her body and and then in blood these words.....
"Aren't you glad you didn't turn on the lights?"