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Fifteen volunteers spent 40 days in cave with no natural light or clocks. Most want to go back, here’s why… © Human Adaptation Institute

Christian Clot on the DEEP TIME experiment and living with no natural light

Published: 13th May, 2021 at 14:12
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Read the transcript of our Science Focus Podcast with Christian Clot – scroll down to listen to the episode.

Dan Bennett Around two months ago, a group of 15 people – scientists, explorers and medics – travelled deep into a cave in the south of France. The expedition descended to a point so deep that natural light could not reach them, and there the team stayed for 40 days and 40 nights without clocks, phones or anyway of telling the time.


The project’s goal was to understand what happens to our brains and bodies when we’re deprived of an external measure of time and they hoped to discover how a group of people could adapt to such an extreme situation.

Just two weeks ago, that team emerged from the cave, and Christian Clot, the expedition’s leader and the designer of the DEEP TIME mission, joins editor Daniel Bennett on this week's episode of the Science Focus Podcast to talk about what the experiment discovered, how the expedition changed him and what ultimately happened when the team returned to the surface.


Christian Clot Yeah. Thank you so much. First, all, our main aim is to study adaptation, how humans can adapt themselves to new kind of situations, a new environment or things that suddenly hit us. And we have to find solutions in a way, unfortunately or fortunately, I don't know any way we would have more and more of these situations when things would completely change and mainly for us as and being in U.K. or France, because we are used to have an easy life in a way. We have less knowledge about how we can suddenly change completely our way of doing things when suddenly things change. And we saw that with the covid-19, of course, suddenly we had to change a lot of things. We look down on the we live. It was a bit hard for a lot of people. And we saw that during the last year and we had a study about it where we saw a lot of people who were completely lost in this situation and lost track of time, in fact. And people were telling us, I don't remember if I have to eat, if I have already eaten what I have to do for tomorrow. So they were a bit lost in the situation. So mainly I figure that we had this time issue situations that we had to try to build and experimentation about this idea of time. Specifically time the deep time project is the idea of that. I mean, putting some people in a cave without anything outside and. No light, sunlight, no clock, as we said, no watches, no all these kind of things. And yeah, it was pretty amazing.

Dan Bennett So before you went in, did you have any hypotheses? Did you have any ideas as to what might happen if you sent this? Was it fifteen people? And did you have any theories about what you might see?

Christian Clot Yeah, we had firstly because we we of course had some some information from other kinds of experiences, mainly Michel Schiff, who did some experiences in the 60s and 70s in France, on other people in Germany, also on the try to to live in a cave without time. But they were alone. And so we had nice experiences and they saw two things. Some of them had a rhythm a bit different, like twenty five hours per day, mainly others had forty eight hours where they lived. Forty eight hours instead of twenty four. So we knew that we will experience some change off of time, some change of rhythm. But we had our information from experimentation like Mars 500 you know. But then again all that wasn't really interesting because the new one thing is that it was experimentation, but it was just to try to, to test things. And that didn't really live a real environment, which is really important because when you are in a in a building, in, you know, it's experimentation in your brain. You know that it's just a game in a way. You suddenly try to to find solution. OK, if I had to live here for my whole life, what would I do? That's the idea of a cave. So we mixed the Michel Schiff experimentation and Mars 500 different kind of experimentation to try to build a new kind of project in real environment, but without time,.

Dan Bennett So what were your living conditions like was normal?

Christian Clot The cave is huge. I mean, it's it's really amazing how big is it? And we were able to walk inside and to visit the cave. It was really, really beautiful. so mainly who had three spaces in the cave. One was the base camp and we had a nice place with a cooking stove and in a food and all to have some some fun and nice time in a way. So it was really a rest area on the base where we were living mostly during the day. Other space, five hundred metres far from here, was a place where we were sleeping with tent. We each have a tent and a sleeping bag and all of our facilities. And so it was our space. We were alone. Each of us were alone in the tent. So it was really is a place where we had some time for ourselves and to sleep. Other places were for science. So we we we had a little building inside the cave to run some science experimentation and the fourth place. It was, of course, the cave itself. And so all the space we had in the cave, it's a two level cave. The first level is where we were living on second level, 90 metres down inside the earth. We had a nice other places where we had extreme exploration time. So all these spaces were places we were living in and working in and experiencing. It was really amazing.

Dan Bennett What was it like when you were walking in and going in for the first few days?

Christian Clot Well, it was a really amazing and disturbing experience. I mean, the first night was really disturbing. I mean, you wake up in the middle of the night, but I do not know that. It was just fully dark because in a cave you don't have any light. So you wake up and first thing we do is to just check your smartphone to see, you know, what time it is. And I don't have this. Did I slept enough how many times I slept. It's impossible to know about. So you just have to accept that you don't have to to to try to understand time, but you just try to understand your own feeling then I feel good that I feel sleepy or not not sleepy anymore or can I wake up. And so for the first few nights we need to adjust and to try to accept that. OK, I have just one information. It's my feeling, my emotion. I have to listen to them. And it's really disturbing because we're not used to do that in a normal life. So each of us was feeling the same and trying to adjust to these kind of conditions. And we talk a lot. Whoa, what time is it for you? I don't know. I just slept enough or not. No, I want to go to sleep again. I want to eat. And everyone everyone of us was just trying to adjust. And finally, it took us at least five, six days. I mean, considering our time to adjust to this. Plus, we had a lot of things to do. I mean, we were we had to learn about cave on to organise our camp and organise our system and really, really do when we had to do. And suddenly, after mainly ten days, we were so tired. So nothing left, nothing more happened. We were just, whoa, what are we doing here? It took us five, six days. Where we didn't did anything, in fact, we were just trying to do something that nothing happened and we were completely in different rhythms. Some were sleeping when some were awake. And we had all or every time, every every single moment someone awake. And it was completely crazy. And then again, after six, seven, eight days, we decided we had to change things. And we we figure some goals and we decided to work together a bit more on then again, change the way we organise our time. And it was much easier, in fact.

Dan Bennett Light.

Christian Clot We had a big light in the food area, which we can light on off. It was a decision we made all together and all the rest of the time or in the rest of the of the cave we had just our small personal lights. So it it was really amazing.

Dan Bennett Did find that your cycles eventually really synched up?

Christian Clot Yes, in a way, yes. Well, of course, we all had our own rhythm and some were sleeping a lot some were sleeping only some few hours. But I was, for example, feeling that my life was normal. After some adjustment, I was thinking, OK, it's mainly roughly must be twenty four, twenty five hours a day and I sleep enough just usually I sleep on it for about four hours and a half and it's enough for me. So I was feeling I was in this kind of cycle and the rest of the day I was working and it was normal and I thought really in my head. OK, I have a normal life now. But at the end of this experimentation, when when people came and told us, hey, guys, it's it's finished, you spend 40 days in the cave, it was just so. Oh, how possible is it? I just feel like today is so ten days less. And so it's obviously we had a completely different one outside and it's something that was never observed like that in any kind of other experiences. So we had to analyse what happened for all of us and why we had these huge differences between our time and normal time. The more interesting thing here is that it's much less our biology thtat finally dictates our rhythmn, but the idea of being together and spending time together. So we needed two things. We needed to follow our own rhythm and to spend enough time sleeping on and any time for us. As a human being, plus to have time for the group doing things together. So I think it's one of the reasons we spend the average of 32 hours per day. So, yeah, that's that's something we have to analyse. It's interesting to see that

Dan Bennett Obviously, we. We all very familiar with where how time can be very fluid, especially when we have a sense of what they call flow, you know, when we're busy doing something we love or a hobby

Christian Clot That's amazing for that because you're right, in a normal life, you always think, oh, it's short time. It's a long time when it's the same second in reality. And we didn't had this kind of of of sensation. We were more thinking. We were always in the right time. And because we didn't have this clock time, normal clock time, we couldn't really compare the feeling we had as a person and the reality of time. So we never thought that. We always thought it's the right time. I spend the right thing and to spend time to read and to to chat with someone and we never thought, is it one hour or two hours it was just the right time. But that was a new sensation. And in fact, I feel and I know a lot of my colleagues feel the same, much more free in the cave because I didn't have to follow a time. I had just all my time. And it's it's amazingly strong as a feeling.

Dan Bennett Yeah, OK, how was your mood?

Christian Clot why it was in a way. Much easier. I mean, what I had I had a I had I was in charge of the group, so I had a lot of things to think. I know that finally at the end of the day, I had much less things to to to think and to do each day. I mean, as you said, no email, no phone call, no recall, your schedule telling you you have to go very quickly and all these kind of things was away and really far away. And it's amazing how fast to just fit nicely with this kind of situation. It's much more hard to go back to this idea. I think that each of us, but one maybe, but mainly each of us feel much more free and much more peaceful inside the cave. And it's why at the end when when we had this information, guys, it's finished now you have to go outside. A lot of us were thinking, would I really go outside? Maybe it's better to stay here. And yeah, it's not a long term thinking because just at the very second we went outside for real and we saw the sun and it was, yeah, I like it.

Dan Bennett Did you have you taken anything with you from that time?

Christian Clot Yeah, in a way, yes. It's well, you know, as as a company manager, I had very quickly to go back to my normal. It Took me like more than one week before I was able again to open a newspaper, for example. I want to know. But if you read information on and I try to put my phone away as much as I can, I can't do as much as I would like. I tried because I really feel like I don't know. I don't know for now, but for sure, I know we have to change something in our life. I mean, we we I saw these people not prepared at all to live in a cave at ten degrees Celsius, at one hundred percent humidity, which is quite hard. And I saw them. And I think while they're happy and I'm more happy than the one, but a lot of people I saw in my in my normal life, it's all I know. It's not the way to live like that in cave. Of course not. And I know I like also being outside. And while it's not a nice time for that, with a covid-19? But to go in a museum theatre and to to spend time with others and to have social life, all these kind of things we love, of course. But I think we need a mix. We need to think much more of what is our time, what is what we're doing each day. We feel we have some devices normally here to help us save lives but at the end of the day, we know that took us a lot of time. So we need to adjust now. I feel really bad. I don't know how I hope I don't have a solution right now, but I know we have to adjust that.

Dan Bennett Were you surprised by how how quickly a group were able to sort of just adapt to that new world?

Christian Clot Yeah, fully. Really. I didn't I didn't think it would be so quick, really. I read, of course, everything was what was all the experimentation in the 60s, 70s. And I saw by the experience a lot of pain to adjust and to adapt and the experience also some mental trouble. So I was really afraid. In fact, I was preparing myself a lot to help people and to think, well, maybe I would just fall down on my guys will fall down too what I was really focussed on. If I see something, I have to immediately do something to help someone else. And I know obviously after five or six days, everybody was fine. Of course, we had some little issues sometimes when people felt suddenly, oh, it's it's a bit long. I want to change things. I don't want to be alone. Or I don't want to be, again, was a group. And we had some things like normal, normal things, but we supported that. And I really thing now I'm pretty sure of two things. The first thing is that the group is the best system to synchronise people together. I mean, it's amazing how strong the group is and much more than a group. The diversity inside the group is really, really important. I built the group with normal people in normal life, but we have really different ways of thinking. We're all different. And they came from all social system and different places in France. And so they are all really different. And so that each time we had. A problem or something happened, someone has a solution on offer, a solution, and if everybody is ready to listen to others and finally, it's easier really. It's the first time I see that. I mean, each time I had an argument in just half an hour, it was solved much quicker than in the normal life. So really, I saw that the group, when when they decide to cooperate and work together, had enough diversity to find different kinds of solutions.

Dan Bennett Did you sort of have applicants and you try to you created a special group, maybe special from it, but you created a group based on that kind of thing that you were trying to build the most successful, give the mission the most biggest chance of success. Is that how you selected?

Christian Clot Yes. Well, it's always difficult to build a group like that. I mean, it's it's, again, normal people from every side of society. And of course, they are all voluneteres and all prepared in a way to live in this kind of situation. It's not like you go to suddenly hit by a tsunami where they don't have any preparation. I prepared a bit. It's a month. I talk to them and I talk to them. And so, of course, it's not just normal people. They are a bit prepared for this kind of thing. And they are mostly also I choose for this experiment people. They all we were all ready to collaborate. I think that's something very important. It's not there were nobody just thinking, oh, I'm better alone. I don't want you I don't not like you. And I know it's not like we were all ready to collaborate, but yet you know that when you are tired, when things are difficult, when you didn't eat enough, sometimes just bored and you're not really happy to help other people. So of course you always need to adjust. But anyway, it's of course, It's as an experiment it's biased. I feel for the first time we do that. I can't just put people ready to fight, you know.

Dan Bennett I was reading about the Apollo missions and how they recruited the astronauts and it was very much about collectivist language, people who said. You know, when they said, how would you solve this problem? Their answer is, well, we would do this and we would look to this. And and they particularly, I think, people from farming backgrounds, I think because they had that sense of you, we move as one that's really interesting that you see it time and time again.

Christian Clot in fact, we learn I learn a lot from our expedition and for the selection, for example, I use a lot of what we do for polar expedition and what they do for Antarctica and of course, also for the moon moon expedition, maybe preparing for 2024 for in the States. So we pick a lot of different kinds of things, like to with a way to select my people in this way. In fact, it work well. And I was amazed, really amazed how much we finally spend the time of 40 days without any strong arguments. And really, of course, some work you need to be ready for to discuss at the very moment to see something happen before even it happen. You have to go on to discuss and to separate people, to talk with them and on finding each occurrence. But anyway, at the end of the day, we saw that we were happy inside. That was really nice to see that.

Dan Bennett bit about what sort of things you were measuring. I know there was lots of samples of different things. What were you what data have you gathered to study for the next?

Christian Clot Well, we have mainly free kind of data, roughly. First group of data was biology. So inside temperature, how tissue samples of of blood are always kind of as we usually do in this kind of situation. Of course, how you sleep with some some machine. And that's so yeah, that was biology and normal biology. Second kind of of a term was cognition. And we had a lot of exercises about cognition, of decision making. We were using EEG also to measure brain issues and we did before just after going outside the cave from MRI, which of course we didn't have inside the cave. But it was just the day before entering the cave on the day just after getting outside, we were inside an MRI to have the idea of what change inside the brains of plasticity had been. So this will be very, very interesting because I think it's the first time we we had this kind of experimentation just after this kind of a cave of experimentation. I of course, I we never know everything. So I don't know. I think it's the first time and and yeah. And third kind of thing was mainly emotions. And we try to really figure out what were the emotions and the evolution of all emotions, sensitivity. How do I feel the way I feel about people, what I feel in the morning into the evening, am I sad or happy, always kind of small emotions that I think are really important when when you have to take a decision, because we we are pretty sure. But each kind of decisions are made before by emotions because you feel an emotion to take a decision. And so we need to understand much more emotions, which is really hard, in fact, because we don't have specific devices to measure emotions. So we have skin information to see if people are sweating. alot heart beating are accelerating. So we had a lot of questions raised about feeling the head on a how they fear the situation and all these kind of things. On the fourth, maybe, and the variety of information was, of course, all information about the cave itself. Temperature, I chose a cave because of the wonderfulness you have inside the cave in a normal environment. And I'm pretty sure that wonderful is the feeling you you happy with seeing your environment and and interacting with your environment is really important when we talk about adaptation.

Dan Bennett You know, they were going somewhere and it's the wonder. That's interesting.

Christian Clot You know, I saw the eyes of each of them. We had this second level. So we had to go down and we were open and special equipment. And we go down and we have some lake. We have some little port inside the lake. And it was really, really beautiful. And I saw the eyes of each of them coming back. And I think this is real. It's a reality. I mean, because we are so happy they feel something so strong, they want to go back again. So they have a reason to be here. We have a reason to focus on the next day and after. And so this idea of wonderfulness, I saw that in a lot of my expeditions and different kind of situations. Because you have something that, please you that make you happy. It's a it's a strong reason to to fight again and to pursue it on on your life, on the situation, even if the situation is hard.

Dan Bennett Just quickly moving on and all this data, what's what's next now? What's the next phase? And I gathered all of that huge amount of data

Christian Clot where we have thousands of data we have to analyse. So we have different scientific group. Will took all the information they began to analyse. We have at least 12 different teams working on the data right now. So it will be I hope we will have some information, I hope in some months in out. And I hope we have. And of course, we need to go again in the field. So we have three project now. And of course, we have to do a deep time again. So a second one at least to to just check if we have the same thing happening or if it would be completely different, which would be. And and I hope some other teams will work also on this kind of situation. So I'm really fully open to help our team to work on this kind of experimentation with other groups of people and have the same group of people, the very same group of people who were in the cave. We will go in some different kind of environments till the end of the year. And in 2022, we will go in the rainforest desert area to check if it's the environment or is the strongest system to to synchronise or if it's to people, if it has the same way of adapting themselves, whatever the environment is, or if for each environment to have a different way of adapting. So it will be very interesting because it's the first time the same group of people will go in different kind of environment. And it will be very interesting about the brain issue.

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