Living without time: The cave experiment we didn't want to end

Christian Clot is an explorer who travels to the world's most inhospitable places to try and survive. But recently, he worked with scientists on something a little different. Christian took 14 others into a cavernous cave system in south-western France to see what happens to humans' perception of time in the absence of clocks and natural light. They spent 40 days inside and did not expect to react the way they did when told the experiment was over. Get in touch: outlook@bbc.com Presenter: Kevin Ponniah Producer: Kevin Ponniah Picture: Volunteers leave the Lombrives cave after spending 40 days in darkness, April 2021 Credit: FRED SCHEIBER/AFP via Getty Images