Ana Breit’s journey into the world of hibernation began with her studies on body temperature regulation. Initially focusing on bats, she was intrigued by their ability to double their weight before entering a prolonged hibernation state. A year ago, Breit joined the Duke Lemur Center as a research scientist, where she began studying the Malagasy fat-tailed dwarf lemurs. “Being able to study hibernation in the closest relatives to humans able to hibernate is an incredible opportunity,” said Breit. Her team, alongside colleagues at the Duke Lemur Center, secured a $30,000 NC Biotech Flash Grant to explore hibernation at warmer temperatures.
While science fiction often portrays humans in cryogenic sleep during lengthy space journeys, the reality of such “synthetic hibernation” presents numerous health challenges, including potential cognitive decline. To preserve cognitive function, synthetic hibernation in humans might require warmer temperatures than traditional cold-weather hibernation. This is where lemurs come into play.
The Role of Lemurs in Space Exploration
The Duke Lemur Center houses the only colony of fat-tailed dwarf lemurs in human care. All research at the center is non-invasive, utilizing two state-of-the-art hibernacula rooms that can each accommodate up to ten hibernating lemurs. These facilities allow researchers to control ambient temperature and simulate Madagascar’s light cycles, which signal hibernating animals to prepare for winter. Metabolic rates are measured using respirometry equipment, while radio collars track skin temperature.
Researchers hypothesize that hibernating at warm temperatures—sufficient to maintain essential homeostatic processes and cognitive function, yet cool enough to conserve energy—is crucial for the success of long-duration space missions. Human hibernation in space could significantly reduce the need for food and oxygen, prevent muscle and bone deterioration, and alleviate boredom or loneliness during extended voyages.
Comparative Studies and Field Research
While hibernation has been extensively studied in rodents like ground squirrels, no primate or tropical mammal was known to hibernate until a 2004 study by German researchers published in Nature revealed that fat-tailed dwarf lemurs can hibernate for up to seven months in tree holes. These lemurs store fat in their tails, which can account for up to 40% of their body weight.
Breit’s research compares two groups of lemurs: one experiencing extreme daily temperature fluctuations and the other in a stable environment. Hibernating mammals need to rewarm periodically. Lemurs in fluctuating temperatures can passively rewarm daily, conserving energy, while those in stable conditions must actively rewarm, expending more energy and depleting fat reserves.
Breit is also investigating how hibernation affects immune function and inflammatory responses. Collaborating with researchers nationwide, she aims to determine if these and other processes shut down during certain hibernation phases, which could indicate potential health risks for hibernating humans.
To ensure lab findings mirror natural behavior, Breit’s team conducts a concurrent field study in Madagascar during the island’s dry season. Antonin Andriamahaihavana, a PhD student at the University of Antananarivo, partners with the Duke Lemur Center to study wild dwarf lemurs in their native habitat, collecting energetic data in naturally fluctuating environments. This fieldwork validates lab results, ensuring the research reflects the natural hibernation traits of lemurs.
Cognitive Function and Future Implications
Cognitive testing is another critical aspect of the study. Dr. Brendan Johnson, a DLC veterinarian and primate cognition researcher, leads memory and problem-solving tests. Lemurs are presented with puzzles, often motivated by treats like half a craisin. Their performance is evaluated based on the number of levels completed and the speed of task resolution. These tests are repeated post-hibernation to assess cognitive changes, addressing the question: “After astronauts wake up, are they still able to drive the spacecraft?”
Breit’s research builds on foundational work by previous Lemur Center researchers. The infrastructure, protocols, and baseline data they established allowed her to immediately pursue high-impact questions. “If they hadn’t started the hibernation program here, I wouldn’t be able to conduct the research that I do,” said Breit. “It allows me to build off questions they’ve already asked. And I can add different layers to it that make it even stronger.”
What began as a curiosity about body temperature has evolved into a mission to help humans sleep their way to the stars—guided by the rhythms of tropical lemurs, the precision of modern science, and the power of interdisciplinary collaboration.
