Waking up this morning

This morning when i got out of bed i noticed the floor looked a lot messier than from last night. I walked over to the light switch and ended up stepping on a dvd case. I then realized my whole entire rack of dvd came crashing down on the floor in the middle of the night. What i'm still trying to figure out is how the sound of 50 dvds falling at the same time didnt wake me up.