Man crawling out of uninhabited bear hibernating den (not recommended). Credit: IStock

As the days grow shorter, many animals, such as bats, bears and bees, begin getting ready to hibernate. It’s a process that allows animals to spend the winter months conserving energy by reducing metabolism, oxygen consumption and body temperature. So why don’t humans do it, too? Well, a new study suggests that some humans—specifically those with chronic fatigue syndrome (CFS), which affects more than 2.5 million people in the U.S.—may be doing something similar to hibernating.

People with chronic fatigue syndrome experience extreme fatigue. But this is not your run-of-the-mill kind of post-holiday exhaustion. It is severe fatigue that does not get better, even with sleep. People with CFS may also experience issues related to memory and headaches. It’s not clear why people develop the disorder, but some theories point to infections, exposure to chemicals or stress as possible causes.

The new study, published in the Proceedings of the National Academies of Science, looked at specific molecules (metabolites) that are byproducts of energy production (metabolism) in the blood of people who have CFS and healthy people who do not have the disease. The researchers found that people with the condition had 80 percent fewer metabolites compared to the healthy control subjects. Those with chronic fatigue syndrome also had some impairment in the way their metabolism functioned. The findings suggest a less active metabolism in people with CFS similar to metabolic activity seen in animals that hibernate. Reduction in metabolic state is thought to be a defensive strategy all humans can use to cope with situations in which environmental or other stressors are present. The problem for people with CFS is that this defense mechanism stays turned on, slowing metabolism—and draining energy—on an ongoing basis.

What’s great about this study is that researchers and clinicians finally have a set of chemical markers in the blood that they can use to test people for CFS. The hope is that by understanding what’s going wrong, metabolically speaking, a treatment can be developed.

Karen Sweazea, PhD, is an associate professor in the School of Nutrition & Health Promotion and the School of Life Sciences at Arizona State University.