I've always heard that bears aren't true hibernators, that they sleep. Googling "do bears hibernate" I find the overwhelming majority of scientific articles say they don't hibernate.  "It is a common misconception that bears hibernate during the winter. While bears tend to slow down during the winter, they are not true hibernators. Black bears, Grizzly bears and Brown bears do go into a deep sleep during the winter months, known as torpor." So says an article at bigcat.org.