Sleeping lemurs, deep sleep, and space travel

By Casey Frye, CCNN Writer

baby sleeping
Enter a much deeper sleep than this baby.

Even though researchers have conducted several studies on sleep, no one really understands why we need it. Some scientists have hypothesized we need it to form memories, while others presume sleep is important for conserving energy. A more recent discovery uncovered resting replenishes brain cells worn down during the day! Despite all these possibilities, however, no one can give a definite answer as to why we need it. “If we spend nearly a third of our lives doing it, it must have some specific purpose,” said Andrew Krystal, a sleep medicine physician at Duke. In order to find out why, he and a group of researchers studied the fat-tailed dwarf lemur!

Hey, I thought they were trying to find out why we humans sleep! Why did they use animals? Apparently, lemurs are the closest mammals related to humans that hibernate. This might instantly make you think of a bear sleeping snugly inside a cave, am I right? However, hibernating doesn’t always mean sleep. Instead, it refers to seasonal changes animals experience in their bodies, which includes a decrease in breathing and body temperature regulations. In a state known as torpor, the fat-tailed dwarf lemurs are able to slow down heart rates from 120 beats per minute to a mere 6, and breathe only once every 20 minutes! In addition, they don’t regulate their body temperature, you know, by doing things like shivering when it’s cold outside and sweating when it’s hot! Instead, their temperatures fluctuate with those in the environment. As a result, they are able to rest in a sleep-like state for more than half a year!

The researchers then asked themselves: since regulating body temperature is supposed to be a function of sleep, and the lemurs don’t regulate it, does it mean they don’t need as much sleep? Apparently not! You see, when humans sleep, we experience two stages: rapid eye movement (REM) and non-REM. The latter (the second of the two) stage is most important for feeling well-rested. When the researchers examined the fat-tailed lemurs, they didn’t show any signs of non-REM, so it’s like they weren’t sleeping at all! “If you completely deprive animals of [non-REM] sleep, then they die,” Krystal said. “And yet the lemurs that hibernate appear to be able to go for months without sleep… and they’re not dying.”

What does this mean for humans, though? “Hibernators do live longer than non-hibernators,” said Krystal. “It looks like the time [the lemurs] are hibernating is added onto their lives.” Woah, is this another doctor who’s trying to tap into the fountain of youth?

Not quite. It has more to do with people who are waiting for organ transplants. You see, every breath and every heartbeat brings them one step closer to death. If researchers can find a way to slow their hearts down safely – say, by inducing them into a state of hibernation – they’d have more of a chance to stay alive! The same can be said for astronauts who may travel for long periods of time in future space explorations. If they can hibernate instead of just sleeping regularly, the daring space-travelers can penetrate the furthest reaches of the galaxy!

Featured image courtesy of Frank Vassen on Wikimedia. Image of sleeping baby courtesy of psgreen01 on Flickr.