Is there anything wrong with her. If she is pretty normal than she is not just lazy, she is uncaring.
Is this a trend? Is she trying to send a message.
If she hates the 12 hour shift she may be deliberately making your life hell to get you to stop. If that, however, is not the case than trade her in. If she is forty, go grab 2 twenty year olds. Fifty, get to 25 year olds.