Humans In Dark Isolation Develop 48-Hour Sleep Cycles, Sleep 30 Hours
Isolation messes with our heads. Humans who lose contact with other people and the normal stimuli that occurs during the day react in strange ways. One of the weirdest things that our iso-brains do is change our sleep cycle until we're out for up to two days at a time. Admittedly, this is an extreme example, but multiple researchers have found that they don't just lose track of time, their sleep cycle in isolation changes from seven or eight hours a night to 48 hours at a time. In every case, these researchers have no idea how long they're actually sleeping because it just feels normal.
Even if you aren't sleeping in a cave beneath the Alps, your body and mind can warp in isolation. Staying inside for days on end can make you lose track of time and sleep as if you're in a kind of soft hibernation. Researchers are still trying to understand why.
Isolation Changes Our Perception Of Time
It's not a stretch to imagine that without any way to tell time, our grasp of the hours and days slip away. Researchers who've spent long periods in isolation have found that "time-shifting" is a normal part of isolation. In 1961, French geologist Michel Siffre abandoned his watch during a two-week expedition of a glacier beneath the French Alps in an attempt to discover how humans deal with darkness and extreme solitude, and before he knew it, two months had gone by. Siffre maintained contact with his team above ground, who discovered that his perception of time had stretched over the course of his stay beneath the Alps to the point that it took him five minutes to count to 120 seconds. It's no wonder he didn't realize that entire months of his life slipped away.
The 48-Hour Sleep Cycle In Isolation
What researchers have found after studying the isolation of Maurizio Montalbini, as well as scientists Josie Laures and Antoine Senni, is that our isolated bodies adjust to a new schedule (if that's what you want to call it) in which we sleep for up to 48 hours in one cycle. In 1993, Montalbini spent 366 days in an Italian cave that was designed by NASA to simulate space missions, but when he returned to life above ground, he believed that he'd only spent 219 days in the cave. This lapse in his perception of time was caused by his sleep-wake cycles nearly doubling in isolation, without any clear reason why.
As horrible as all of this sounds, Montalbini's research into isolation has helped scientists get a somewhat tenuous grip on what happens to our internal chronometer when we're left to our own devices for long periods of time. That being said, we're still a long way from understanding why our bodies lengthen our sleep cycles.
Our Internal Clocks Need The Sun
The most likely reason behind our extended sleep cycles in isolation is the lack of sunlight. Without something for our biological rhythms to lock into, we simply drift further away from our normal sleep cycles, and natural light is the most obvious method of synchronization to our bodies. It's what the Germans call our zeitgeber, and without it, our sleep patterns can't synch up to the 24-hour day that normal people experience on Earth. When Antoine Senni returned from isolation beneath the French Alps (it's apparently a popular place for it) in 1965, he was aghast at the knowledge that he'd been underground for two months longer than he believed. With no way to measure his time, he simply slept and slept.
Permanent Jet Lag
It's one thing to say that we sleep a lot in isolation, but the nuts and bolts of this occurrence are still somewhat nebulous. The best way it can be described is like a major case of jet lag. When we take a trip across time zones, it takes our bodies a while to adjust to our destination's time cycles because they need to synchronize with the natural light in our new environment. If we remove ourselves from our synchronizer (the Sun, a clock, etc.), our bodies never adjust, stuck in a permanently jet lagged condition.
This is an imperfect way to describe what happens to our bodies and minds in isolation, but it feels accurate, especially if you've spent any time locked indoors by yourself. You may not be depriving yourself of the Sun, but with days and nights that are indistinguishable beyond the Sun going up and down, we still find ourselves feeling sluggish and looking for excuses to stay in bed.
Boredom = Sleep
Like others, when Josie Laures lived underground for months in the 1960s while being monitored by fellow scientists above ground, she slowly drifted out of her normal sleep pattern without the Sun to guide her body. Most notably, she found that she slept for long periods of time when she didn't have anything to do, although she believed that she was only taking cat naps. After leaving the cave, she told the Associated Press:
I can tell you though that it became very difficult toward the end and I felt terribly worn out ... At the start of my stay, I read, and then I lost the desire. I didn't suffer from the cold. I was well heated in my little tent. My tape recorder refused to work the first few days, but later, I managed to repair it, and I listened to music. Outside of that, I knitted and knitted some more and looked forward to the time when I would finally see the Sun.
What Laures shows us is that when the human body lacks stimulation, especially in an extreme situation, we just fall asleep for days. It's unclear if this is because our bodies know that there's nothing for us to do or if we just shut down, but whatever the case, the propensity toward giving up remains a universal human constant.
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