Hibernation: The Long Nap of Animal World
- theexploreroffice
- Aug 7
- 7 min read
Updated: Aug 9
In the year 2073, Dr. Brand and Mr. Cooper received a signal from Dr. Mann, 1,900 light-years away from Mann’s planet. The signal was clear:
“There’s a potential for life here. The temperature looks cold on the surface, but beneath it, in the valleys, the temperature and oxygen levels are suitable for human existence. Here, I am attaching some data.”
Excited, Dr. Amelia Brand and former engineer Mr. Cooper boarded the spacecraft, traveled through a black hole, and reached Dr. Mann’s planet. It was a frozen world, with temperatures dropping below -20 degrees Celsius at night, appearing inhospitable for human life. Yet, when Dr. Mann landed on the planet back in 2073, he had sent out signals suggesting the possibility of life there.
Dr. Brand and Cooper tracked his location upon landing and made their way to his pod. They opened the large metallic circular door and entered the chamber from which Dr. Mann’s signal was coming.
But Dr. Mann was nowhere to be seen. He was asleep—or more technically, hibernating—in a capsule.
Mr. Cooper slowly opened the plastic enclosure in which Dr. Mann lay. Within seconds, Dr. Mann awoke from his “long nap.” Seeing Mr. Cooper beside him, he immediately began crying like a baby. The odds of ever seeing another human face had seemed so slim that just laying eyes on Cooper overwhelmed him with emotion.
Hibernation had preserved Dr. Mann long enough to survive the vast emptiness of deep space.
This outstanding scene from Christopher Nolan’s Interstellar showcased fascinating scientific phenomena—from black holes to time dilation, from hibernation to the fifth dimension of space. These concepts and more will be explored in future issues of The Explorer. But today, we focus on the concept of hibernation.
Imagine this: a world where humans hibernate. Just like bears do in winter. A world where people in colder regions would sleep through the harsh, freezing months—five to seven months per year, tucked away in warmth and rest. It sounds like science fiction, but what if it could become science fact?
In areas where temperatures drop below 15°C (as shown in the black regions on climate maps), over three-quarters of the global population—some 4.5 billion people—could potentially hibernate. During that time, they wouldn’t need food, water, or consumer goods. Our fossil fuel use would plummet, and the ecological impact of humanity would shrink dramatically. In essence, we would be giving the Earth a seasonal break.
If we could reclaim the time spent in hibernation, we might even live longer. Consider this: the life expectancy of a 10-year-old Dutch girl today is about 80–90 years. But if she were to hibernate half of each year, she could theoretically live to be 175. She might even give birth to her first child at 64.
While the idea sounds appealing and even utopian, the reason for exploring human hibernation goes beyond curiosity—it’s rooted in medicine.
To understand how humans might hibernate, we first need to understand how other animals on this planet are already doing it.
In the animal kingdom, many species live in extreme cold climates or face seasonal food scarcity. There are two primary ways of dealing with these harsh conditions:
1. Migrate to southern places where there is no food scarcity
2. Take a long nap until the winter is over
To migrate, an animal needs longer and stronger legs and must weigh less in proportion to its size. Only then can it travel thousands of kilometers to a new habitat. A prime example of this is the mass migration of caribou, a type of North American reindeer.
Caribou graze on grass, mosses, and other vegetation in Arctic plains during summer.
But come winter, the ice frost and extreme cold in the northern regions make survival difficult. So, they begin migrating south—covering roughly 50 kilometers a day. A herd of 100,000 caribou moves together, walking over 2,500 kilometers south. They manage this epic journey because their strong legs are built for long-distance travel. But not all animals are so well-equipped.
Birds, for example, have a high surface area relative to their body volume—a disadvantage during extreme cold. Their bodies lose heat quickly because of the larger surface area of their skin. This is why the majority of northern bird species migrate south for the winter. Birds like flycatchers, wrens, geese, flamingos (see image below), and others that typically live in Siberia or Northern Europe begin flying in flocks—sometimes as far as 4,000 kilometers—to Africa or even Australia in some cases.
But what if you don’t have strong legs like caribou or wings like birds? What option is left?
This is where the concept of hibernation comes in. Are you ready to explore it? Yes? Then, let us go.
What is Hibernation?
Hibernation is a state of significantly reduced metabolic activity that some animals enter to survive extreme environmental conditions, such as cold or food scarcity. While we typically associate hibernation with frigid climates, animals in hot regions like Africa also hibernate.
During hibernation, an animal lies down in a comfortable, soft cushion made of straws—often beneath the surface of the earth (though not always)—and stays there for five to six months in a sleep-like state without eating much. This helps them avoid the harsh winter.
So, how do they do it? I mean, don’t they need food, need to urinate, or stretch out at some point?
First Things First: Food
Before entering hibernation, animals fatten up—some, like squirrels, increasing their body weight by as much as 50%. They even induce a temporary, diabetes-like state to store fat efficiently. Yet, unlike humans, they don’t suffer from clogged arteries or other metabolic issues commonly associated with obesity.
The North American black bear spends nearly 20 hours each day during autumn gathering fat from food. It ends up consuming as much as 20,000 calories per day—five times its normal diet! The goal is to become as heavy as possible so the stored fat can be used as energy throughout the five-month-long nap. Now, how can a Bear eat five times its daily calories requirement without puking it all out? The portion of brain which controls the feeling of contentment is called Hypothalamus. When scientists experimented on rodents by cutting down the connection of Hypothalamus with other part of the brain, the rodents kept on eating without ever feeling content. Something similar happens in the case of a black bear.
All of this fat accumulates under the skin, forming a layer up to 5 inches thick. This fat layer not only provides energy but also serves as insulation, protecting the bear’s internal organs from the cold.
But the true key to hibernation isn’t fat storage—it’s metabolic suppression. Animals slow their metabolism drastically, allowing their body temperature to fall to match the environment. This process is called torpor, and it alternates with short bursts of intense warming called arousals. See the graph above.
Why do hibernating animals periodically rewarm their bodies? No one knows. It’s one of the great unsolved mysteries of biology—so important that if there were a Nobel Prize in biology, solving this could win it.
Next Thing: The Heart
Now that the issue of food is resolved, how about parts of the body laying dormant for months at a stretch? Don’t they get destroyed?
When a part of the body doesn’t get exercise, the muscle tissues inside it start to dissolve. Bones become hollow and less dense over time due to inactivity. So why doesn’t the same happen to animals during hibernation?
Ground squirrels hibernate by curling up (see image). This reduces the surface area exposed to the outer, colder climate. Now, remember—they stay like that for months during winter, sleeping. A normal heart rate for a squirrel is about 350 beats per minute (for comparison, it’s about 72 beats per minute in humans, so you can imagine how fast a squirrel’s heart beats!). During hibernation, their heart rate drops to just 2 beats per minute. Can you imagine? Check your wristwatch and see how long 30 seconds feels when the heart beats only once or twice in that entire time.
Bats (not the Batman) normally have heart rates between 300 and 500 beats per minute, and it can go as high as 1,000 beats per minute while flying. But during hibernation, their heart rate slows down to just 10 beats per minute.
And it’s not just heartbeats—other body processes also slow down. Metabolism, brain temperature, and many other internal functions reduce drastically for protection and survival.
Finally: Pooping
Black bears have an extraordinary ability to recycle their waste. Urea (a waste product from protein metabolism, which we usually excrete through urine) is broken down and reused. The nitrogen from urea is used to build new proteins, which helps the bear maintain muscle mass and organ tissue during hibernation—even without eating.
Before hibernation, bears form what’s called a fecal plug—a dense mass made of indigestible materials (like hair, plant matter, etc.) that collects in the colon. During hibernation, this plug prevents anything from leaving the digestive tract. When the bear wakes up in spring, the first thing it usually does is expel this plug.
Since bears don’t eat during hibernation, there’s no new food passing through the digestive system. That means there’s no need for regular digestion or waste production. Their metabolism shifts into a super low gear, focused only on survival—not digestion.
Why do we want to hibernate as humans?
Besides what we already saw earlier, where 4.5 billion people of earth can sleep for 4-5 months, solving the global warming crises, the implication for medical science in near future could be enormous.
By combining cooling and protective compounds, we could:
1. Preserve organs longer for transplantation
2. Buy time for trauma, stroke, or heart attack patients
3. Reduce bleeding and immune response during surgery
4. Safeguard astronauts and bed-bound patients from muscle loss and blood clots
And this is just scratching the surface.
So, can humans hibernate?
Not in the traditional sense. We’re unlikely to fatten up in summer and sleep through winter anytime soon. But we can harness the biology behind hibernation.
Controlling metabolism is, in a sense, controlling life. The more we learn about the secrets of hibernation, the closer we get to transforming medical care—and maybe even how we live our lives.
Nature, after all, has already solved many of the problems we face. The answers are out there.
All we need to do is look.
Would you, dear reader, like to sleep for 5 months a year after eating nice food? That would be a dream, wouldn’t it?
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