You probably already know that bears hibernate through the winter. They find a cozy den to curl up in, and sleep the cold months away–all without waking up to eat (or even go to the bathroom). Scientists always thought that when the bears slowed their metabolisms so they could sleep for so long without eating, their body temperatures would drop dramatically. A new study says that this isn’t the case.

Alaskan black bears do lower their body temperatures while hibernating, but only by about 9 to 11 degrees Fahrenheit (5 or 6 degrees Celsius). Other body processes slow down as well. The bears’ heart rates dropped from about 55 beats per minute to about 9 beats per minute! How well would humans do with heart rates like slumbering bears? “If we had that kind of longer interval within our heartbeats, we would probably faint,” said study co-author Øivind Tøien, a zoophysiologist at the University of Alaska, Fairbanks.

Read more about the bear study on National Geographic News.

Get the facts on brown bears, or grizzly bears, in the Creature Feature.

Photograph from All Canada Photos/Alamy