Deep Time Study; 40 Days in Cave

Picture the scene; fifteen young people are confined together in a dark cave for forty days without the ability to track time.

Researchers just carried out such an experiment in the Lombrives cave in Ussat les Bains, France and the results were fascinating.

The temperature in the cave was fixed at 50 degrees F (10 degrees C) and the relative humidity pinned at an oppressive 100%; on top of all this the team had to rely on artificial lighting.

In an interview after their 40 day stint they were asked as a team how long they thought they were in the cave, they answered 30 days, with one individual offering up 23 days.

That they lost track of ten days was astounding to researchers and was indicative of how we rely on clocks or the day-night cycle to tell time.

This goes to show how unreliable our internal clock system is, even across the relatively short time span of 40 days.

The team was monitored by researchers outside the cave; sensors tracked their every move from sleep patterns, to social interactions and body temperature as well as other metrics.

The organizers of the Deep Time project chose a cave setting instead of a lab for their experiment because it’s easier to study human responses in a natural environment; rather than in simulation in a small enclosed space.

Remarkably, two-thirds of the participants said they would’ve stayed longer in the cave if they could, but some, such as Johan Francois, struggled at times, saying he had “visceral urges” to leave.

Francois kept busy by walking upwards of 6.2 miles (10 km) each day, which he did by walking in circles around the cave perimeter.

Marina Lançon, one of seven women to participate in the experiment, said the experience was “like pressing pause” on her life, and she’ll avoid her smartphone for at least a few more to days to avoid a “brutal” return to regular life.

Without clocks or the setting Sun, the team had to rely on bodily cues for when to go to sleep, when to wake up, and when to eat. The team tracked time not by days, but by accumulated sleep cycles. Fascinatingly, the group mostly stayed in synch, despite being divorced from “real” time.

But as the results showed, they became very poor at evaluating the length of each day. Given their 30-day estimate for the 40-day stay, the team figured that each day was about 32 hours long, on average.

By the end of the experiment it was probably much worse, and probably closer to 40 hours. As for the team member who thought only 23 days had elapsed, their “day” was 42 hours on average, and again, probably even longer by the end (i.e. the temporal drift likely didn’t immediately kick in).

These are wild results.

It means that team members went to bed later and later each day, erring on the side of longer, rather than shorter, days. The team was in synch for the most part, but clearly some individuals experienced their own sense as to the passage of time (makes one wonder if there was dissent about when to go to bed).

How the researchers will make sense of these findings and translate them into real-world strategies will be very interesting.

One thing’s for sure; the team members now probably value the inexorable rising and setting of the Sun in a way they never realized they would.