In the room with all the shelves and sand on the floor, get the stick and a sack from the wall. Hide in the closet once prompted.
After getting out of the closet, go to the once-locked bottom door in the small medicine room. Then run.
Return to the glass maze and face the unreachable stairs. Use the stick to break the wall. Pick up one of the glass shards. Go up and get another note from the wall in the back room.
Enter the door where the Sandman started chasing you. Make sure to grab the mirror on the table to get around the castle faster. Keep going, and show the second note to Lullaby when you find them.
When the statue starts singing, do four of these five things to wake yourself up: bang head on statue, use the stick, play music with cellphone, splash face with bucket of water, yell out a window. (Make sure not to use the mirror here, or you'll lose it for the rest of the game.)