Humans aren't built for darkness. Yet, in 1989, Stefania Follini crawled into a plexiglass module buried thirty feet underground in a New Mexico cavern. She stayed there for 130 days. No sunlight. No clocks. No one to talk to but her own thoughts and a computer named "Homer." When we talk about women in a cave, Follini’s name is the one that usually surfaces because her experience shattered what we thought we knew about the human body’s internal rhythm. It wasn't just a stunt; it was a cold, hard look at how the female biology reacts when the world disappears.
People get this story wrong all the time. They think it was just about loneliness. It wasn’t. It was about science—specifically, NASA-funded research into how astronauts might handle long-term isolation in space. But Follini’s stint in the Lost Cave near Carlsbad proved that women might actually be the ultimate endurance athletes of the mind, even if their bodies pay a bizarre price.
The Day the Sun Stopped Rising
Imagine losing the concept of "Tuesday." Within weeks, Follini’s sense of time didn't just drift; it evaporated. She started staying awake for twenty or twenty-five hours at a stretch. Her "days" became erratic cycles that bore no resemblance to the 24-hour rotation of the Earth. This is what chronobiologists call "free-running." Without the sun to reset the suprachiasmatic nucleus—the tiny cluster of cells in your brain that acts as a master clock—Follini’s internal pacing went wild.
She lost weight. Tons of it. Around 17 pounds, actually. She stopped menstruating entirely, a fact that fascinated researchers like Dr. Maurizio Montalbini, who pioneered these isolation studies. Her body basically decided that since the environment was so alien, it was time to shut down non-essential systems. It’s wild to think about. Her brain was fine—she was sharp, reading hundreds of books and playing cards with herself—but her endocrine system was essentially screaming "error 404."
Why We Keep Putting Women in Caves
You might wonder why scientists chose women for these high-stakes isolation tests. Honestly, the data suggests women often handle the psychological "crunch" of isolation differently than men. While men in similar cave experiments often reported higher levels of irritability or aggression, Follini remained remarkably composed. She decorated her cave. She kept a meticulously clean environment. She focused on the internal world because the external one was just rock and silence.
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But Follini wasn't the only one. There’s a long, weird history of women in a cave pushing the boundaries of human limits. Take Veronique Le Guen. In 1988, just a year before Follini, she spent 111 days in a cave in France. She wanted to see if she could maintain a normal life. She couldn't. Like Follini, her menstrual cycle vanished. She suffered from profound depression after emerging, proving that while the body can survive the cave, the mind often leaves a piece of itself behind in the dark.
These experiments weren't just for kicks. They were foundational for what we now know about:
- Seasonal Affective Disorder (SAD)
- The necessity of "blue light" for circadian regulation
- Sleep hygiene for shift workers
- Long-duration spaceflight psychological profiling
The Biological Toll Nobody Talks About
We need to talk about the bones. When you stay in a cave, you aren't just missing a tan. You're missing Vitamin D. Follini’s calcium levels plummeted. Because there was no natural light to trigger Vitamin D synthesis, her body couldn't effectively process calcium, leading to concerns about bone density loss. This is the same problem astronauts face on the International Space Station, but they have specialized gyms and supplements. Follini had a small module and some books.
What’s even crazier is the sleep architecture. Most people think if you're tired, you sleep. In the cave, Follini would sometimes sleep for ten hours and feel like she’d only had a nap. Other times, she’d stay awake for two days straight and feel "fine." Her body was trying to find a new equilibrium, a "cave rhythm." It turns out the human body’s natural cycle, when left entirely alone, might actually be closer to 25 or 28 hours rather than 24. We are literally forced into a 24-hour day by the sun.
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What This Means for You (Without the Cave)
You don't have to live in a hole in New Mexico to learn from this. Most of us live in "digital caves" anyway. We spend 90% of our time indoors under artificial lights that mimic the stagnation Follini felt.
If you want to keep your internal clock from breaking like hers did, you've got to be intentional.
Get bright light within 30 minutes of waking up.
This is non-negotiable. Even if it’s cloudy, the lux levels outside are thousands of times higher than your kitchen light. It pins your circadian rhythm to the start of the day.
Stop eating when the sun goes down.
Follini’s digestion became a mess because she was eating at "random" times relative to her body's expectations. Your gut has its own clock. If you eat at 11 PM, you’re telling your gut it’s noon, while your brain knows it’s midnight. That conflict causes inflammation and brain fog.
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Vitamin D is a hormone, not just a supplement.
The bone loss and menstrual changes seen in cave experiments highlight how vital Vitamin D is for hormonal regulation. If you’re a woman working in a windowless office, you are essentially in a "lite" version of Follini's cave. Test your levels. Don't guess.
The Modern "Cave" and Mental Resilience
There’s a weird trend now called "darkness retreats." People pay thousands of dollars to sit in a dark room for a week. They say it triggers a DMT release in the brain or leads to spiritual enlightenment. While the science on the DMT claim is shaky at best, the psychological reset is real. When you strip away the "noise" of the modern world—the notifications, the traffic, the constant visual stimuli—you're forced to look at your own "operating system."
Follini’s 130 days showed us that women are incredibly resilient in these environments, but at a high physiological cost. She came out of the cave thinking she had only been there for about 60 days. Her perception of time had slowed down by half. That’s the most haunting part: the cave stretches time.
Actionable Steps for Circadian Health
To avoid the "cave effect" in your daily life, implement these three specific changes:
- The 10-Minute Sun Rule: Stand outside for 10 minutes every morning before checking your phone. The light hitting your retinas sets the timer for your melatonin production 16 hours later.
- Temperature Cycling: Follini’s cave was a constant, cool temperature. Our bodies need a drop in core temperature to initiate deep sleep. Keep your bedroom at exactly 65-68 degrees Fahrenheit to signal to your brain that the "day" is over.
- Blue Light Blockers After 8 PM: If you must use a screen, use high-quality orange-tinted glasses. Standard "blue light" filters on phones often aren't strong enough to stop the suppression of melatonin that mimics the "always-on" state Follini experienced underground.
The legacy of women in a cave isn't just a quirky bit of 80s news. It’s a warning. Our biology is deeply, perhaps irrevocably, tethered to the movement of the planet. When we sever that connection, we don't just lose track of time—we start to lose ourselves. Keep your lights bright in the morning and your nights dark. Your hormones will thank you.