There are many expressions used to indicate that someone slept soundly. I'm not sure if you're looking for expressions or for a more literal way to communicate the same information. sdgraham's response is the best way to communicate it literally, in my opinion.
A few more expressions are:
"She was dead to the world."
"She was sawing logs all night." (Sleeping soundly and snoring)
"She slept like a baby."
"She was out like a light."