01/05/2025
The Scientist Who Spent 6 Months in a Cave to Understand Time
What is time? Is it something that exists outside of us—or is it created by our own minds? One brave French scientist, Michel Siffre, put his entire life on the line to find out.
We all live by time. We wake up when the sun rises, eat at certain hours, and go to sleep at night. Clocks, calendars, and the movements of the sun and moon help us keep track of our days. But what if all those external signs disappeared? Would our minds still be able to feel time?
In 1972, Michel Siffre set out to answer this mystery. He did something no one had dared before: he chose to live completely alone, deep underground, in total darkness—for six months. His goal was to explore how the human mind and body experience time without any outside clues like daylight or clocks.
Siffre entered a cave in Texas, about 440 feet below the surface. It was not just dark—it was pitch black and completely silent. He had no way to know if it was day or night. The only things he had were basic supplies to survive. His research team stayed above ground, monitoring him from afar. He could contact them by phone, but they were not allowed to initiate contact. They carefully recorded his eating, sleeping, and behavior.
At first, Siffre tried to stick to a regular schedule. But as time passed, his sense of time completely changed. Hours felt like minutes. Days seemed to blur. He had no idea how long he'd been in the cave. Was it day? Was it night? He didn’t know.
Soon, his mental state began to deteriorate. He started hearing voices and seeing things that weren’t there. He even began to think someone else might be in the cave with him. Loneliness and sensory deprivation took a deep toll on his mind. He even began talking to insects, just to feel less alone. At one point, he said hearing his own voice echo in the cave gave him comfort—until silence returned.
What Michel didn’t know was shocking: by the second month, he thought only 24 days had passed. In reality, nearly 48 days had gone by! His body had shifted into a new rhythm: 36 hours awake, 12 hours asleep. Without sunlight or time cues, his brain had created its own clock, different from the usual 24-hour cycle. Scientists were amazed. This proved that the human brain has an internal time system—but it needs external cues to stay aligned.
As weeks turned into months, things got worse. Michel began to forget how to speak properly. His memory declined. His emotions became unpredictable—he’d go from happy to deeply depressed in moments. He later described the experience as “a slow descent into madness.”
Finally, after 180 days, Siffre was brought out of the cave. He believed only 151 days had passed. He had lost track of nearly a month! He was shocked. He had truly lost his grip on time.
This experiment revealed something powerful:
- Time is not just external.
- Our minds actively shape our experience of it.
Isolation and sensory deprivation can distort that sense—sometimes dangerously.
Michel Siffre’s findings had a huge impact. They helped shape modern research in sleep science, space travel, and psychology, especially for people in isolation like astronauts or prisoners. But he paid a high price—his mental health took years to recover, and some memory problems lasted a lifetime.
Still, Siffre didn’t stop. He went back into other caves, repeated his experiments, and confirmed his earlier findings. His work changed how science views time and the human mind.
And yet, one question remains:
"What is time, really?"
Is it something real, out there in the universe? Or something created inside us?
Michel Siffre’s life suggests it may be *both*. As he once said,
"The human mind is a universe in itself."
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