Without time, without light - How do the brain and body react? | DW Documentary

Deep Time Experiment Summary

Key Concepts:

• Adaptation: Adjusting to new life situations, progressing from suffering to stability and long-term survival.
• Neuroplasticity: The brain's ability to rewire neural connections based on environment and experiences.
• Chronobiology: The study of the influence of daylight (or lack thereof) on human sleep and biological clocks.
• Desynchronization: The drifting apart of individual sleep-wake cycles within a group deprived of time cues.
• Temporal Memory: The imprint of time from the outside world that humans carry with them.
• Cycles: A waking phase and a sleep phase, used as the unit of time measurement in the cave.
• Phases of Adaptation: Discovery, Apathy, Resolution/Adaptation.

1. Experiment Overview and Objectives:

• The "Deep Time" experiment, conducted in the Lombrives Cave in the French Pyrenees on April 24th, 2021, involved 15 volunteers living underground for 40 days without any external time cues (no sunlight, clocks, or communication with the outside world).
• Led by explorer Christian Clot, the experiment aimed to study how the human brain perceives time and adapts to extreme conditions, specifically the absence of day-night alternation.
• 30 scientists specializing in neuroscience, chronobiology, and sensory systems monitored the participants.
• The primary research question was: How do humans react when deprived of all timekeeping devices and the alternation of night and day? Will they become disoriented, and how will their senses react?
• The experiment sought to understand the brain's adaptive mechanisms and neuroplasticity over a 40-day period, something not previously studied.

2. Background and Motivation:

• Christian Clot has spent 20 years studying human adaptation to extreme environments, initially as a subject himself.
• The Deep Time experiment was inspired by the loss of the sense of time experienced by many during the COVID-19 lockdowns.
• The experiment builds on previous cave studies from the 60s and 70s but focuses on cognitive function within a group setting.
• The Lombrives Cave was chosen for its spaciousness and constant temperature (10°C), providing a comfortable environment for the team.

3. Scientific Team and Their Roles:

• Stefan Bernard (Medical Researcher): Analyzed the effects of sunlight deprivation on spatial perception and balance. He used virtual reality to assess changes in balance and orientation.
• Peru Torah (Behavioral Scientist): Monitored the behavior of the social group in an extreme situation, focusing on adaptation in the absence of time cues.
• Etienne Klein (Neuroscientist): Studied neuroplasticity using medical imaging (MRIs before and after the experiment) to analyze changes in brain structure (gray matter density) in areas related to memory (hippocampus), decision-making (prefrontal cortex), and visual processing (visual cortex).
• Benoit Mauvieux (Chronobiologist): Studied the influence of daylight deprivation on sleep patterns and how biological clocks function in a group setting.
• Katel Thiephon (Pathologist): Analyzed surveillance camera footage of the communal living area to observe the subjects' behavior, interactions, and presence.

4. Participant Selection and Preparation:

• The 14 participants (referred to as "deep timers") were selected from over 1,000 applicants.
• They underwent months of physical and psychological testing.
• The group included individuals with diverse backgrounds, such as a doctor, biologist, nurse, industrial climber, and goldsmith.
• Participants were trained on the scientific protocols, including how to use the sleep study equipment (polyomnography) and participate in virtual reality tests.

5. Experiment Protocol and Daily Life:

• Participants lived in the cave for 40 days without any time references.
• They were free to eat, sleep, and engage in activities whenever they wanted, regardless of others' schedules.
• Daily activities included:
  • Performing essential duties (e.g., food supply management, water collection).
  • Riding a stationary bike for one hour per day to charge batteries.
  • Participating in approximately two hours of scientific testing.
  • Maintaining a mini vegetable garden illuminated with LEDs.
• Waste and data were regularly dropped off at a designated location and collected by a support team to avoid contact with the outside world.

6. Key Findings and Observations:

• Desynchronization: Participants' sleep-wake cycles quickly drifted apart. Emily, the nurse, desynchronized rapidly, sleeping for up to 30 hours at a time.
• Phases of Adaptation: The experiment revealed three distinct phases:
  • Discovery: Initial euphoria and high activity levels.
  • Apathy: A period of lethargy, reduced social interaction, and decreased activity. Social interactions fell from 1,000 to fewer than 300 between the third and fourth weeks.
  • Resolution/Adaptation: The formation of smaller groups, increased exploration of the cave, and a renewed sense of purpose.
• Sensory Changes: Participants became hypersensitive to visual information, particularly dynamic visual stimuli, due to the lack of light. The area of the brain responsible for object recognition seemed to have partially atrophied.
• Social Clock: The group developed a "social clock," where frequent moments of communal life served as points of reference and collective reactivation.
• Neuroplasticity: The experiment challenged the notion that the adult brain is fixed, demonstrating significant variations in brain structure (gray matter density) after just 40 days due to environmental conditions. Unlike pilot experiments where Christian was alone, there was no decrease in gray matter in areas specializing in considering other perspectives, highlighting the importance of the group.
• Prolonged Cycles: The average length of a day-night cycle for the participants was approximately 33 hours, longer than the standard 24 hours. There was considerable variability in cycle length, ranging from 25-26 hours to 60 hours.
• Blackout Event: A 24-hour power outage proved to be a traumatic but ultimately unifying experience, highlighting the importance of light and prompting participants to create a more positive environment.

7. Significant Statements:

• Christian Clot: "As the lockdowns progressed, people started to lose their sense of time. That intrigued me."
• Christian Clot: "Seeing this sadness made me realize straight away that the experience has been a complete success. Because if people are sad to leave, it's because they feel at home here."
• Etienne Klein: "What deep time showed us and is very important to us was we needed to change our conceptions of the adult brain."
• Participant: "It started out as a joke to donate my body to science while I'm still alive. to fully disconnect even from time. It'll be incredible."

8. Conclusion:

The Deep Time experiment provided valuable insights into human adaptation, neuroplasticity, and the perception of time in the absence of external cues. The study demonstrated the brain's remarkable ability to adapt to extreme conditions, the importance of social interaction in maintaining cognitive function, and the existence of distinct phases in the adaptation process. The findings challenge existing assumptions about the adult brain's plasticity and highlight the need for further research on how to minimize the period of apathy during adaptation to challenging environments.