Hibernating Dwarf Lemur Reveals Secret of Sleep in Humans

A hibernating lemur may offer new insight into the secrets of sleep in humans. The adorable fat-tailed lemur can go for days without the deepest part of sleep during its winter hibernation. The findings reveal a little bit more about the science of sleep and why we as humans spend a third of our lives doing it.

Why we sleep is still a mystery, despite years of research. Theories range from conserving energy to processing information and memories to removing toxins that have built up while we're awake. Another theory, though, may be the correct one. Researchers believe that sleep may have something to do with regulating our temperature and metabolism. In the case of the fat-tailed dwarf lemur, this last theory seems to be the case.

About the size of a squirrel, the fat-tailed dwarf lemur hibernates for about seven months per year. At that time, the regulation of body temperature stops and metabolism slows down. In fact, in torpor these lemurs can drop their heart rate from 120 beats per minute to a mere 6. In addition, their breathing slows to a crawl and their body temperatures can fluctuate by as much as 25 degrees in a single day, matching the outside air temperatures.

For most mammals, a change in body temperature by more than a few degrees can be life-threatening. With this lemur, though, this hibernation is a good way to conserve energy during Madagascar's long winter dry season, a time when food and water are both in short supply.

In order to study torpor and sleep, the researchers decided to investigate whether lemurs in torpor could get away with less sleep. They attached electrodes to the animals' scalps and then returned them to their nests for monitoring. This allowed them to study lemurs hibernating in the wild and also non-torpid animals sleeping in captivity.

It turns out that dwarf lemurs in torpor went for days without the slow-wave, low-amplitude brain activity associated with deep sleep. However, they did show periods of brain activity consistent with the phase of sleep known as rapid eye movement (REM) sleep. But this only occurred when temperatures rose above 25 degrees Celsius.

So what does this mean? It shows that metabolism has a huge role to play when it comes to why humans sleep. In addition, by identifying similarities between dwarf lemurs and other hibernating animals, researchers may be able to induce the same hibernation-like state in humans. This could help buy time for patients who have suffered head trauma or heart attacks.

The findings are published in the journal PLOS One.