Hibernating Lemurs Hint At The Possibility For Human Hibernation, Say Duke Researchers
The fat-tailed dwarf lemur of Madagascar, the only primate known to hibernate, could provide insight into whether hibernation in humans is possible, say Duke researchers in a study in PLoS ONE. The possibility of human hibernation could have wide-ranging applications in everything from emergency rooms to space shuttles, according to the researchers.
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"[The fat-tailed dwarf lemur] is the closest genetic relative to humans that hibernates and is therefore the most likely to be providing useful information to understanding things like what is the capacity to induce hibernation-like states in humans," said Andrew Krystal, director of Duke's medical school's sleep lab and author of the study.
Hibernation in mammals doesn't mean "sleeping for a long time," though it does look like that's what's going on. Rather, it's a state of "profound reductions in metabolism, oxygen consumption and heart rate." Sleep during this state may not even be deep: in the study of the fat-tailed dwarf lemurs, the researchers found that the primates went for days without going into deep sleep.
During its hibernation, or torpor, the fat-tailed dwarf lemur's heart rate dropped from 120 beats per minute to only six. Unlike most mammals, the fat-tailed dwarf lemur doesn't regulate its body temperature during this hibernation, or torpor. Its body temperature can vary by up to 25 degrees during a single day during torpor. In most mammals, that great a fluctuation in body temperature, during hibernation or otherwise, could be dangerous.
"There's a lot of mystery left" following the study, according to Krystal, including why the fat-tailed dwarf lemur hibernates in the first place. But if one primate is able to hibernate, if we could induce hibernation in another primate -- humans -- Krystal imagines any number of possible benefits.
"If we wanted to travel to some point in outer space that took 100 years, how could we possibly do it? We would have to induce a period of hibernation that would allow a person not to need to function for a period of time in order to get there and survive and return."
Terminally ill patients could benefit hugely from hibernation too. Taking in oxygen and constantly pumping blood is taxing on a sick person. In the fat-tailed dwarf lemur, breathing during hibernation only occurs once every 20 minutes, with a heart rate that drops by 95 percent. A terminally ill patient, slowed down to such infrequent breathing and heart pumping, could hang on much longer and be treated. If the patient were in need of an organ, he could wait for a longer amount of time until a suitable donor was found.
While no one really knows if it's possible to induce hibernation in humans, Krystal believes it may just be. If lemurs, our genetic relatives, can do it, "it now seems likely that we have the genes that hibernators have -- it is just that those needed to hibernate are not turned on or turned off to allow this to happen."
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