The Sciences

What Happens When Humans Are Extremely Isolated?

Science studies have isolated humans in caves and underwater for weeks and months at a time, testing the limit of the mind and body.

By Tree MeinchMay 25, 2023 10:00 AM
(Credit: dickcraft/Shutterstock)


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Humans have evolved to survive and thrive as social creatures. Meaning, dynamic cooperation and connection to others are fundamental to our existence as a species.

And yet, or perhaps because of this, some individuals insist on pushing the limits of human isolation. They voluntarily subject themselves to extreme environments and conditions to test what the human body and mind can endure.

Living in Social Isolation

Over the past century, scientists have monitored human subjects while they voluntarily isolate in caves, outer space and even under the ocean for up to months at a time. In extreme scenarios, scientists have even tested the limits on themselves. 

While some of the late experiments would likely be deemed unethical (or denied funding) in today’s world, athletes and individual researchers continue to advance this daunting field in extraordinary ways.

100 Days Under the Ocean

Since March 1 of this year, an associate professor at the University of Southern Florida has been teaching all of his classes online — while he’s living alone 20-some feet below the ocean in Key Largo, Florida.

Surpassing 73 days in confined isolation earlier this month, Joseph Dituri, aka “Dr. Deep Sea,” set a new world record for the longest anyone has continuously lived underwater in a fixed environment.

He’s planning to continue until June 9 to complete a 100-day stay inside Jules’ Undersea Lodge. (The former underwater research lab is now a 100-square-foot recreational destination and overnight room-for-rent that is only accessible via diving.)

As a researcher in hyperbaric medicine, Dituri is documenting this science expedition with a support team under the name Project Neptune 100.

Atmospheric Pressure and Health

One central goal of the research is to evaluate the effects of long-term living under extreme atmospheric pressure and confinement, which can apply to space missions as well as water exploration.

The research to date in this field is quite limited. Beyond the risks of decompression sickness, living under the sea alters the partial pressure of oxygen in the human body.

Technical saturation divers, who work on pipelines or other commercial infrastructure up to 1,000 feet deep, often spend weeks living in pressurized chambers to adjust to the extreme environment. And even following proper protocol, headaches, fatigue and other ailments routinely occur.

Read More: Join a Scientist's Undersea Adventure

Risks and Possible Benefits of Underwater Living

Living underwater, even in a cabin or pod, can often cause superficial skin infections or rashes that become dangerous if not treated.

Factors like the lack of sunlight, high humidity, and limited sanitary measures in the environment all pose challenges to long-term living. In Dituri’s case, physicians conducted a series of physical tests before he departed for the lodge, have visited him inside his pod during his stay, and will take more tests upon his return to compare results.

So far, Dituri has reported to the Washington Post that he’s experiencing more REM and deep sleep during rest and his cholesterol and stress levels have dropped while living at depth.

As a military veteran with a Ph.D. in biomedical engineering, Dituro is particularly interested in the potential benefits of pressurized environments for treating traumatic brain injuries — an emerging field of study with mixed findings and some controversy.

Living Underground in Caves

On dry land, caves have a longer and more robust history of extreme human isolation trials. 

As far back as 1938, University of Chicago physiology researcher Nathaniel Kleitman and an assistant spent 32 days isolated in Mammoth Cave in Kentucky. Their research concerning internal circadian rhythms and temperature cycles in the human body was later published as a book, Sleep and Wakefulness.

In a more extreme feat, French scientist Michel Siffre spent two months in 1962 in cave isolation, with no clock, natural light or calendar.

He went on to conduct a series of similar experiments on other human subjects before dedicating himself to a six-month cave stay in 1972. “I decided to live like an animal, without a watch, in the dark, without knowing the time,” he told Cabinet Magazine in a 2008 interview.

Siffre's research and fascination with the internal biological clock laid much of the groundwork for the field of human chronobiology.

An Italian sociologist, Maurizio Montalbini, also contributed greatly to this field, reportedly spending a cumulative two years and 18 months isolated in caves over the course of his life.

What Does Isolation Do to a Person?

In recent decades, hundreds of people have now isolated in different caves or lab simulations (both short- and long-term) for the sake of scientific evaluation.

This includes Spanish climber and cave-dweller Beatrice Flamini who just last month emerged from a record-breaking 500 days of isolation in a cave.

Similar to many test subjects before her, Flamini expressed disbelief that her target date had already arrived when the researchers came to relieve her of her stay. She said it felt like time hardly passed at all, while immersed in the dark, consistent environment.

In some of Siffre’s experiments, he reported that test subjects naturally shifted into a 48-hour sleep-wake cycle, rather than the solar-based 24-hour period that governs most of our lives today. They would be active for 30-some hours, then sleep for 12 or more hours.

In one instance, Siffre has said, his team recorded a man sleeping for more than 33 hours continuously. Listening with a microphone, researchers grew concerned that the subject might have died in isolation — then they finally heard him snore.

Read More: Why Cave Dwellers Enjoy Isolation

Effects of Isolation in Caves

The mix of studies on cave isolation have illuminated a range of unique physiological reactions in humans.

These include augmented heart rates, vitamin D deficiency, muscular damage and inflammatory responses as well as irregular menstrual cycles.

One experiment involving a 27-year-old woman staying 131 days in Carlsbad Caverns, New Mexico, also showed a significant drop in red and white cell counts upon entering isolation, and then swift recovery of that count.

With all the findings, however, the gold standard of replicated results has been hard to come by, according to a comprehensive review of the research.

This leaves many questions unanswered about the universal effects of long-term isolation on the human body and mind.

Is Space Lonely or Peaceful?

The varied results also suggest that a vast range of personal variables might shape the experience based on the individual involved. And better yet, it’s hard to truly understand these experiences from an outside lens. 

One anecdotal example of this unfolded in 1969, when the world watched as NASA astronaut Michael Collins orbited the far side of the moon on the Apollo 11 mission — all alone while his two fellow crew members descended to the lunar surface.

“Not since Adam has any human known such solitude,” is the way NASA described Collins’ unprecedented journey into isolation.

After his return, Collins described the trip as anything but isolating. “I was not lonely. I had a happy little home in the command module,” Collins insisted in a 2019 panel interview, rejecting a narrative touted in many news headlines at the time. “Behind the moon, it was very peaceful.”

As space missions are now aiming far beyond the moon — with humans likely to travel much longer distances in confined quarters — continued isolation research might make all the difference on the wellbeing of future astronauts.

Read More: The Human Body Might Survive a Mission to Mars Better Than Our Minds

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