Bear bones remain strong during long sleep

Hibernating bears don't lose bone tissue when they catch their zzz's, scientists have found. They say the finding could provide clues to fight osteoporosis in humans.

Researchers analysed blood samples from black bears hibernating in Virginia.

Unlike in humans, the researchers found the bears don't suffer profound bone loss while inactive for long periods.

Bone regeneration often tends to slow or stop in people who are inactive because of disease or injury.

Scientists don't know why bears are immune to the bone thinning.

Team member Sean Donahoe of the department of biomedical engineering at Michigan Technological University suspects a hormone or other chemical could be the key.

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The researchers hope to do follow up studies to test their hormone hypothesis.