THE LOST TAPES OF DR. MICHEL SIFFRE

What you are about to read is based on a TRUE story. Michel Siffre is 100% REAL and actually did this!

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by Sean Dempsey, 04/02/25

A Chronicle of Isolation, Madness, and Savage Darkness

In the early 1970s, as Cold War psychology and space exploration collided with radical ideas about human consciousness, a lesser-known but brilliant French geologist and temporal theorist, Dr. Michel Siffre, stepped forward with a proposal so bold it was initially dismissed by his peers as reckless. Siffre, formerly affiliated with the University of Toulouse, had spent years studying the intersection of geology, circadian biology, and psychological thresholds. He was particularly fascinated by time—not as a mechanical measurement, but as a perceptual experience, a living function of the brain.

His obsession was influenced heavily by the work of Laurel Chaflour, a fellow French speleologist who, a decade earlier in 1962, had famously sealed himself in a cave for two months without clocks or sunlight. Chaflour’s study revealed that the human brain, when deprived of environmental cues, gradually loses its ability to track time reliably. His findings revolutionized our understanding of circadian rhythms and laid groundwork for astronaut isolation research.

But Siffre wasn’t interested in space. He believed that beneath the Earth, in its untouched, unknowable hollows, the mind could be pushed further than Chaflour dared. His theory was radical: that time itself, like pressure and gravity, was a force shaped not only by physical laws but by the presence of consciousness. And that in the total absence of external inputs—light, time, sound—the mind would either evolve… or collapse.

In early 1972, Siffre secured private funding from an obscure institute with connections to both French military intelligence and experimental psychology circles. He designed his study around total isolation: no light, no clocks, no human contact, no sensory input beyond touch and his own voice. The plan was to remain in an uncharted Pyrenean cave, 440 feet below ground, for at least 180 days.

He would bring:

• Basic rations for 200 days

• Water stored in sealed tanks

• A sleeping bag and hygiene kit

• Multiple cassette tapes and ten 4-packs of AA batteries.

• A single audio recorder, into which he would dictate logs daily or as close to “daily” as his perception allowed

Notably, he brought no watch, no artificial light, and only one red emergency flare he vowed not to use except in a true crisis.

The scientific world, if it knew of the experiment at all, forgot about it. No publications. No news.

He was never heard from again.

Nearly a year later, spelunkers searching a collapsed section of the mountain discovered a small hollow chamber—impossibly deep and barely accessible. There was no sign of Siffre’s body, no equipment, and only one item remained: his tape recorder.

The following transcripts were recovered from those recordings.

They began scientific.

They ended… something else entirely.

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TRANSCRIPTS FROM THE RECORDER OF DR. MICHEL SIFFRE

—Recovered from a failed cave isolation experiment in 1972—

Reconstructed from analog tape recovered beneath the Pyrenees. Each log begins with his own estimation of time passed. No external timekeeping device was used.

[Audio Log: Day 1]

Voice: Calm. Measured. Professional. Background static minimal.

“This is Dr. Michel Siffre. Entry one. June 3rd, 1972, by my last known calendar reference. Commencing Isolation Study Number One.

“I have descended into the primary cavern system beneath the eastern Pyrenees, at an estimated depth of 440 feet. The chamber is vast and structurally sound. Dry. The silence is… profound. Even my own breath seems to hesitate before echoing. There is no light, by design. My last exposure to sunlight was just before entering. I will not see it again for approximately six months.

“I have brought with me 200 days of rations, water, a sleeping roll, and this recorder. No clock. No calendar. No light source, save one emergency flare. The objective: observe the effects of total isolation and darkness on human circadian rhythm, cognition, memory, and perception. I will record entries as often as my internal perception allows. I expect time will stretch and compress. I expect dreams. I expect confusion.

“I do not expect madness. I am trained. Grounded.

“I am ready.

“End log.”

[Audio Log: Day 6–7?]

Voice: Even, but slower. Minor static hum.

“I estimate this is day six, or seven. It is difficult to judge. I’ve been marking meals and sleep cycles, but the rhythm is already… slipping. I mark notches on the wall as a rudimentary timekeeping device.

“I sleep longer than I intend to. Or not at all. I lie awake sometimes, waiting for tiredness, and when it comes it hits like drowning. Hunger is the more reliable compass, though even that has become erratic.

“The silence is heavier than I anticipated. Not simply the absence of sound—it’s like the cave absorbs intent. When I speak, it returns nothing. As if the rock itself resents my voice.

“I’ve begun speaking aloud before I record as a means to prime the stillness. To tame the darkness that has forgotten I exist. A way to remind myself I’m still here. Still me. Still human.

“I feel fine. I feel… thoughtful. Lonely, but focused.

“No anomalies to report.

“End log.”

[Audio Log: Day 14–15?]

Voice: Weary. Speech more fragmented. A soft scraping noise occurs briefly in the background.

“I think… fifteen days. It may be more. Or less. My timekeeping is disordered.

“I awoke from a dream of voices whispering my name, but when I listened closely, it wasn’t my name at all. Just… sound. Wind through cracks. A syllable repeated that had no origin. Isssirrra… Issssirrra… Over and over.

“I haven’t spoken aloud in what I believe is two or three cycles. My throat hurt when I started recording. That surprised me.

“Last night—again, if ‘night’ applies—I thought I heard footsteps. Just beyond my bedding. I held my breath. It stopped. When I reached out, there was nothing.

“Perhaps auditory hallucinations are beginning. Expected.

“I remain… objective. I remain Dr. Michel Siffre.

“End log.”

[Audio Log: Day 17?]

Voice: Focused but wearied, deliberate pacing. Background: occasional faint dripping. Static hum.

“I believe this marks the seventeenth day, by my best estimation. I hesitate to assign certainty to the number, as my internal clock feels increasingly suspect. I continue to carve notches in the stone—using the edge of my cooking knife, as the tin shard has grown too blunt. The new cuts are deeper. It feels necessary to press harder now, as though the rock resists my attempts to track time.

“My daily hygiene remains disciplined. I relieve myself at the far recess of the chamber, roughly three paces from my sleeping area. I selected that location at the beginning of my descent for its slight slope and porous floor. Waste drains quickly, and I cleanse my hands with a rationed trickle of water. Not out of necessity, but out of familiarity. Familiarity is a thin thread I must preserve.

“I also find myself speaking aloud far more often than before, and not just for the recorder. Oftentimes simply to puncture the silence. I describe my actions as I perform them, narrating each motion: ‘Now I reach for the water flask,’ ‘Now I tear the ration packet.’ It is oddly comforting.”

Issssirrra…

“I have been cataloging auditory impressions in my notebook. Last cycle, I noted a persistent low vibration, as if something titanic and slow shifted deep beneath me. Seismic activity is not uncommon in these formations, yet this sound felt… willful. Menacing. As though the stone itself judged me and found me lacking. Unredeemable…

“Yet, I remain vigilant. Objective. The mind is a fragile custodian of reality. I must guard mine carefully.”

—Issssirrra. Issssirrraaaaaaa….—

“End log.”

[Audio Log: Day 19?]

Voice: Calm but conversational, slips occasionally into reflective tone. Background: faint, irregular scratching noise.

“Approximately day nineteen. I cannot be certain, of course. The lines I have etched on the chamber wall now number twenty-three, but this morning I ruthlessly slashed at four of them for I know them to be lies! Damned lies and cursed marks on cold, dark stone. But I am not deceived.

“I admit I have grown confused between sleep cycles and waking periods. Nevertheless, I persist in my recordkeeping. Habit sustains clarity.

“My food supplies remain adequate. I consume a ration at what I believe are regular intervals, though I have noticed my appetite diminishing. The portions I consume feel increasingly like ritual offerings rather than sustenance. I chew slowly, deliberately, mindful of every texture. This keeps my senses engaged.

“Regarding hydration: I maintain my daily intake as strictly as possible. Water is life. I ration it sparingly but consistently. I wash my face and hands before rest, though the water feels cooler than before. The ambient temperature of the cave may be dropping, though my instruments to verify this are, regrettably, nonexistent.

“There is an emerging pattern along the wall to my left, just above my carved notches. A darkening, perhaps mold or mineral seepage. Yet when I run my fingers over it, it feels dry and warm, almost pulsing faintly beneath the skin of the rock. I have begun tracing the outlines with my thumb before each rest period. It feels… vile. Cold. Familiar…

“I continue to hear indistinct noises during my rest cycles. A shuffling, perhaps, or shifting stone. Natural settling, likely. I have ruled out rodents. The air is too still. No droppings, no scrapings of claw.

“I tell myself this is all natural. The mind plays tricks in isolation. I remain scientific in my observations.

“I, remain, Dr. Michel Siffre…

“End log.”

[Audio Log: Day 21?]

Voice: Tight, more hurried. Over-articulation at times, as if forcing composure. Background: irregular tapping, possibly finger against recorder.

“Day twenty-one, or thereabouts. Time continues to elude precise measurement, but my wall markings and my sleep intervals suggest this approximation.

“Hello?…

…

“My routine remains intact, though altered. I relieve myself mechanically, as though my body simply follows an old memory of need. Yet my digestion has changed—less frequent, less urgent. My stomach no longer gnaws at me with the familiar pangs of hunger. There is an emptiness, but it is not discomforting. It is quiet. Perhaps the body adapts more swiftly to deprivation than I anticipated.

“I spend considerable time now running my fingers along the carved wall—where the dark patterns have spread further. I note the growth has formed into looping spirals, reminiscent of ammonite fossils. I did not place them there. No, of course not. But they comfort me in their familiarity. As does the gentle, persistent hissing which comes in waves. Hissing in the darkness which now soothes my senses when it suddenly appears. It is a wave of unexplainable joy to face the hissing instead of the far more damnable silence. The ever-present silence that gnaws at me. The interminable silence that erodes all semblance of hope or joy…

“But I am redeemed. The silence has recently changed character. Once oppressive in its totality, it now feels occupied. Not with sound, precisely, but with presence. The air feels thick, expectant. As though the cavern itself listens when I breathe, when I speak.

“I have found myself whispering to the darkness, without fully intending to. Simple phrases at first: ‘I am here.’ ‘I remain.’ But yesterday, I caught myself asking questions. ‘What are you?’ ‘Why do you watch me?’ I do not remember deciding to speak these words.

“I have received no reply.

“Not yet…

“I, remain … Dr. Michel Siffre?

“End log.”

[Audio Log: Day 23?]

Voice: Uneasy. Measured pauses. Background: what may be breathing, hard to isolate.

“Day twenty-three, possibly. The corruptible notches continue to lie!

“Last night, I reached out in the dark and my hand touched something warm. I froze. Then it was gone.

“I told myself it was my imagination. It must have been. But the air smelled different after. Like… copper. Wet metal.

“There are sounds now. Constant, low-frequency hums like something enormous turning far beneath me. I press my ear to the rock and it’s like hearing the bones of the earth grind.

“I feel watched. It’s subtle. But real. Like a weight behind me. Never ahead. Never face to face.

“I have begun sleeping with my back to the wall. That helps.

“A little.

“Hello?”

—silence—

“Is it you? I know you are there!”

—silence—

“End log.”

[Audio Log: Day 35–37?]

Voice: Paranoid. Words quicken. More background noise—something like wet dragging.

“There are patterns in the stone. Raised veins, like scar tissue, curling along the walls. I swear they weren’t here before. I’ve touched them. They’re warm. Slightly.

“I dream of eyes. Not seeing me … but opening slowly in the dark, lids of stone cracking like shells. I know the cave dreams with me.

“I woke to the sound of something breathing, not me. Slow. Wet.

“I spoke aloud to it. I said, ‘I know you are there, demon.’

“It did not reply. But the temperature dropped.

“They want me to understand them.

“I am trying. Oh, Dear God in heaven, I am trying…

“End log.”

[Audio Log: Day 49?]

Voice: Shaken. Sudden tonal shifts. Faint voices under his speech—unclear if real or overlay.

“I haven’t eaten in… I don’t know. My hunger left me. I offer food now to the watchers. I place it on the stone, and it’s gone by the next waking. I thought cave rodents at first, but there’s no sound of chewing. No droppings. No evidence whatsoever.

“Only absence.

“I saw something move across the wall. Not crawl—flow. Like liquid shadow. Oh, I know to speak of ‘shadows’ in pure and utter darkness may wreak of madness, but I assure you it is not. There can be darkness that is darker than darkness. And darkness leagues beyond that darkness, still. I swear to it! The darkness can and does have shadow!

“As I said, the shadow moved. So I followed it. It vanished before I could reach it. But my handprint was left behind, burned into the stone. A blackened outline. I didn’t press hard. It was like the cave remembered my touch.

“The symbols are growing.

“I hear them when I sleep.

“I think I’m learning their dark language.

“End log.”

[Audio Log: Day 68?]

Voice: Detached. Words smooth, hypnotic. Echo present where there should be none.

“Their names are not names. They are sensations. They speak not through sound, but through time. They compress it. Stretch it. Bend it.

“I have been asleep for years. Or minutes. I no longer know the difference.

“I laid upon the floor and invited them to come closer.

“One entered me.

“No pain. Only weight. Like memory being poured into me.

“I know now—they are pure evil.

“They are old.

“Older than the crust of the world. They were buried by light. They wait for cracks. For silence. For vessels.

“I am ready. So very ready…

“End log.”

[Audio Log: Day 82?]

Voice: Alternates between laughter and weeping. Background: mechanical scraping.

“It is surely day eighty-two? Or twenty-eight? The rock and its gashes mock me. Like wounds in the rock, they bend and weave. They are now all over the rock-face; I struggle to count them all. I surely did not make all these marks! They are the wild and savage dashes of a madman. I swear it is not me who so profaned this cave. I cannot trust the rock, only myself…

“Knowing the rock to lie, I opened my skin to write the truth. I used my own blood. The message fades when I sleep, but they help me rewrite it. Over and over. They guide my hand.

“They have so many hands!

“I feel them now, pressing gently against my back, holding me as I rest. I do not fear them.

“I belong to them.

“I was always meant to.

“End log.”

[Audio Log: Day 93?]

Voice: Barely human. Hollow. The sound of heartbeat—or drums—faintly beneath.

“The cave is opening. Peeling like flesh. The stone breathes in pulses. I can hear the bones of the mountain sighing.

“Their eyes are made of shadow. Their teeth are years sharpened into blades.

“I do not sleep anymore.

“They promised I would become like them. Eternal. Forgotten.

“A vessel of unbeing.

“I will go with them.

“End log.”

[Audio Log: Final Entry]

Voice: Begins in silence. Then a slow whisper. Then screams. Final tape includes rapid distortion and ceases suddenly.

[Silence for 1 minute, 43 seconds.]

Whispers: “I see the gate. I see the great eye behind the world … breathed in flame.”

“They are reaching through now.”

“The stone has vile hands.”

“The stone has sucking mouths.”

“They are tearing me through.”

[Screaming. Long. Ragged.]

[Screaming turns into gurgling. Stone cracking.]

[A low and base whisper, barely audible, and very distorted]: Issssirrraaaaaaaaaaaaaaaa

“I am unmade.”

[End of recording.]

POSTSCRIPT

No trace of Dr. Siffre was ever found. The cavern entrance where the recorder was discovered collapsed days after retrieval. Burn marks charred the cave walls. 

Audio experts verified only one voice present on the tapes—yet there are unmistakably others whispering beneath it.

The tapes were archived and sealed by the funding institution.

The project was quietly buried.

“I go now to explore the dark and brutal depths of time itself.”

-Doctor Michel Siffre, two hours prior to descending into the cave.