The Month in the Dark

Into the Dark

Mara: July 1962. A young cave explorer named Michel Siffre climbs down into the Scarasson chasm, high in the Alps. France's national broadcast archive, the INA, keeps the story. Down there it never gets above freezing, and the air is close to saturated with damp. He's planning to stay two months. No watch. No calendar. No sunlight. Just a telephone line to the surface, in case something goes wrong.

Eli: And the listener's question is a simple one: why does time seem to speed up as we get older? Today's angle is the retrospective memory paradox of aging.

Mara: Most people would guess there's a clock inside us that starts running faster with age. Siffre's two months alone in the dark put that guess under pressure. Down there, his body and his mind are about to disagree.

Eli: Start with the body, then. He had nothing to set it by.

Mara: Nothing but himself. What he sent up to the surface showed his cycle sliding by about half an hour every day. Day after day, the same small slip. His body had settled on a day of roughly twenty-four and a half hours.

Eli: So without the sun, his body didn't collapse. It just ran long.

Mara: His head was another matter. The test was simple. Count to a hundred and twenty, ticking off the seconds like a clock. When he finished, five real minutes had gone by. In his words, 'I psychologically experienced five real minutes as though they were two.'

Eli: His minutes shrank, while that same body kept a near-daily beat. That beat is the circadian rhythm: a daily cycle the body runs on its own, sleeping and waking included, even with no sun to set it. Siffre's barely drifted.

Mara: So there's a built-in day inside him that held. It was his sense of the minutes that went.

Eli: And they can go separately, because it's separate machinery. Timing gets split into three ranges: fractions of a second, seconds to minutes, and the daily cycle. Different stretches of time are handled in different parts of the brain.

Mara: Siffre pushed that split much further in 1972, in a cave in Texas. His days stretched to about forty-eight hours, most of them spent awake. He couldn't tell those from ordinary days. Long afterwards he said, 'The forty-eight-hour cycle is a fact,' but 'nobody understands what could be responsible for such a large desynchronization of the sleep-wake cycle.'

Eli: Double-length days that felt like single ones. A body keeping its own rhythm doesn't mean a mind that knows the date. Mara, the end of that first cave shows how far apart they got.

The Vanished Month

Mara: Back in Scarasson, mid-September 1962. The surface team tells him the experiment is over. Two months are up. And Siffre, as the archive puts it, has completely lost the notion of time. In his head, it's still August. And coming out was brutal. On September 18 he started a hundred-and-thirty-meter climb, and he was very weak. They put large opaque glasses over his eyes to shield them from daylight. He said, in French, 'Je tremble', I'm trembling, asked what was happening, and said he could see his hands shaking. They carried him to base camp and flew him by helicopter to Nice.

Eli: So what did he think swallowed the month?

Mara: He put it down to the darkness itself. The cave was completely dark, with just a light bulb, and he believed his memory simply stopped capturing time. After a day or two, he couldn't remember what he'd done a day or two before. The only things that changed, he said, were when he woke and when he went to bed. Which sharpens the real question. Does an inner clock speed up as we age, or does the brain rebuild time from memory afterwards? Labs have tested the clock part. That's interval timing: judging seconds or minutes as they pass, like sensing a minute is up without a watch.

Eli: Older and younger adults come out about the same on those tasks. The older ones respond more slowly, but just as accurately.

Mara: So age doesn't wreck the inner stopwatch. Siffre's went off at twenty-three, in a cave.

Eli: Where age does show up is looking back. As researchers like Robert Lemlich and Joanna Szadura have it, older people feel the last three to ten years went faster. The effect is modest. And for the past week, month or year, it isn't there.

Mara: Older people time a minute just fine, and still feel a decade slipped past. Siffre's lost month sits somewhere in that gap.

The Memory Mirror

Eli: The pioneering American psychologist William James drew that line. There's time as it passes, and time looking back. Prospective is the running sense of a stretch while it's happening. Retrospective is how long it seems afterwards, in memory. Those two judgments can disagree completely.

Mara: That's Siffre in both halves. Counting in the moment, he ran slow. Looking back, a whole month wasn't there.

Eli: And the looking-back half isn't measured. It's rebuilt. The memory-based account says that as we age, routines get more repetitive and predictable, fewer new events happen, and fewer memorable moments get stored. So later stretches of life seem less full, and shorter. Past time isn't a stopwatch reading. It's a reconstruction from whatever got kept.

Mara: One writer felt exactly that on a trip to Lisbon with friends. In a single day they explored a palace, its tunnels and an initiation well, got turned away from a nightclub, and ended at a beach bar. Each part, he wrote, 'formed an individual episodic memory.' Hours later one friend said, 'It's so weird, yesterday we were in Dublin.' To the writer it felt like three days since they'd left, not one.

Eli: One day crammed with firsts, remembered as three. What the studies comparing age groups haven't settled is why later years keep fewer markers: fewer new memories, or each year being a smaller share of a life. Open too is how a brain lays those markers down and spaces them.

Seams in the Brain

Mara: William James saw the aging side of this in 1890. He wrote that 'each passing year converts some of this experience into automatic routine which we hardly note at all,' so that 'the days and the weeks smooth themselves out in recollection to contentless units, and the years grow hollow and collapse.'

Eli: Lisbon is the reverse: a day with nothing automatic in it.

Mara: And neuroscientists have now watched the brain marking those parts. The idea is event boundaries: the seams where the brain cuts a continuous stream of experience into separate events, like a scene change in a film. When something changed, scans showed strong activity in the ventral tegmental area, a sign of dopamine signaling. More of that activity predicted people judging events as further apart in time. The neuroscientist behind it said dopamine at 'the beginning of a new event is likely one of the ways that our brain segments experiences into memorable episodes.'

Eli: More seams, more remembered distance. And older brains seem to cut fewer. At the Cambridge Centre for Ageing and Neuroscience, researchers scanned five hundred and seventy-seven people, aged eighteen to eighty-eight, watching the same eight-minute Hitchcock clip. They reported that older brains switched between activity states less often. In their words, 'Longer and fewer neural states within the same period may contribute to older adults experiencing time as passing more quickly.'

Mara: Fewer chapters.

Eli: And a second blur sits on top. With age comes neural dedifferentiation: the brain's activity patterns grow less distinct from one another, so different things start to look alike inside. Faces, objects and moments overlap, and it gets harder to tell where one experience ends and another begins.

Mara: Fewer seams, and the pieces run together. Eli, how that turns into whole decades slipping away is the last stretch.

Reconstructing the Years

Eli: Marc Wittmann starts with a caution: 'there is no consensus among researchers on how the brain processes time.' No single clock does the job. But the memory reading he holds points to episodic encoding: the brain taking down a new experience as a memory of its own, details and order included. The sense that the past ten years flew may come from encoding less that's new, not from having fewer life memories to reach. Wittmann puts it as 'the gradual decline in certain cognitive abilities.'

Mara: And all the while, those lab timing scores hold up with age.

Eli: In a 2026 study, people recalled a short list of words after a few minutes' delay. How well they did tracked age. It also tracked how fast the last ten years felt, though not the last year.

Mara: Eli, there's another reading. The proportional theory, held by Robert Lemlich and Joanna Szadura, says each year is a smaller slice of the life lived so far, so each one feels briefer. Wittmann's memory reading says routine leaves fewer rich memories, so those stretches feel faster looking back. What would shift the picture is whether the decade link holds when the same people are followed over years.

Eli: Most of that evidence compares different ages at one moment, not lives over time.

Mara: The complaint itself is ancient. In the first century BCE, Virgil wrote that 'irretrievable time flies.' People have been saying it ever since. What researchers offer back is attention. Wittmann describes 'a relaxed mode of present awareness.' Steve Taylor suggests paying conscious attention to everyday seeing, hearing and feeling, which he says may make time seem to pass more slowly. Journaling and seeking out novelty work the same way: they leave markers to look back on.

Eli: So the answer: time doesn't run faster in the moment as we age. The minutes still measure out right. Past decades feel compressed looking back, because routine leaves fewer new memories and fewer seams to mark them. Siffre went down with no clock and no calendar, and his body kept a near-daily beat. What vanished was a month his memory never cut into days.

Mara: Two more things to watch. Whether those dopamine seams, found in trials lasting about thirty seconds, scale up to years of a life. And whether anyone ever explains Siffre's forty-eight-hour days, the ones he said nobody understood.

Eli: For listeners wanting to read up, start with event boundaries.

Mara: Follow time perception with us as researchers ask how memories shape our sense of passing years.

Eli: Thanks for listening. I'm Eli.

Mara: And I'm Mara. Until next time.