How does your body know what time it is? - Marco A. Sotomayor

Summary

In 1962, cave explorer Michel Siffre conducted groundbreaking experiments isolating himself underground to study circadian rhythms. Despite the absence of external cues, Siffre maintained a regular sleep-wake cycle, revealing the brain's complex timekeeping system, including the suprachiasmatic nucleus (SCN). This system uses proteins like CLK and PER to regulate our daily rhythms. Siffre's time perception also changed in isolation, leading to questions about the subjectivity of time. Ultimately, his research emphasizes how both biological clocks and environmental signals shape our understanding of time.

Takeaways

• 🧗‍♂️ Michel Siffre isolated himself underground in 1962 for months to study circadian rhythms.
• ⏰ Despite lacking external cues, Siffre maintained a regular sleeping-waking cycle, highlighting the body's innate timekeeping ability.
• 🌙 Circadian rhythms influence various bodily functions, including hormone secretion and food processing, and are studied in chronobiology.
• 🧠 The brain contains several internal timekeepers, including a stopwatch, a clock, and a seasonal calendar, each located in different regions.
• 🔬 The suprachiasmatic nucleus (SCN) in the hypothalamus is the primary clock regulating our sleep-wake cycle.
• 🔄 The cycle of proteins CLK and PER drives the oscillation of our day and night patterns, functioning as a biological seesaw.
• 🌞 External cues, or zeitgebers, such as light and temperature, help fine-tune our circadian rhythms in daily life.
• 📺 Bright screens at night can disrupt our sleep cycles by confusing the signals sent to the SCN.
• ⏳ The brain's internal stopwatch uses predictable communication between neurons to create our perception of time.
• 🤔 Siffre's time perception warped while isolated, suggesting that individual experiences of time may vary, raising questions about the objectivity of time.

Q & A

Who is Michel Siffre and what was the purpose of his experiments?

Michel Siffre was a cave explorer who conducted experiments in 1962 to study the effects of isolation on human circadian rhythms by living underground for months without light or clocks.

What are circadian rhythms?

Circadian rhythms are the physical, mental, and behavioral changes in a 24-hour cycle, which respond primarily to light and darkness in the environment. They influence sleep-wake cycles, hormone secretion, and other bodily functions.

How did Siffre's experiments contribute to our understanding of circadian rhythms?

Siffre's experiments showed that even in the absence of external cues, such as light and clocks, the human body maintains a regular sleep-wake cycle, suggesting that circadian rhythms are inherent biological processes.

What is chronobiology?

Chronobiology is the field of science that studies biological rhythms, including circadian rhythms, and how they influence various physiological processes.

What role does the suprachiasmatic nucleus (SCN) play in regulating time perception?

The suprachiasmatic nucleus (SCN) is a cluster of neurons in the hypothalamus that acts as the body's primary internal clock, helping to regulate circadian rhythms based on light and other external cues.

What is the mechanism behind the accumulation of CLK and PER proteins in the SCN?

CLK proteins accumulate in the SCN throughout the day to promote wakefulness, while their buildup leads to the production of PER proteins. Once PER levels are sufficient, they deactivate CLK, inducing sleep, thus creating a cyclical pattern.

What are zeitgebers and how do they affect our daily behavior?

Zeitgebers, meaning 'givers of time' in German, are external cues like light, food, and temperature that help synchronize our internal biological clocks and fine-tune our daily behavior.

How can bright screens at night affect sleep patterns?

Bright screens at night can interfere with the natural signals that regulate sleep by affecting the SCN's response to light, potentially leading to difficulties in falling asleep.

What interesting phenomenon did Siffre observe about his perception of time while in isolation?

Siffre noticed that while he attempted to count to 120 at a rate of one digit per second, his perception of time became distorted, taking him longer to count than it should have, highlighting how isolation can warp time perception.

What implications does the variability of time perception have for our understanding of time?

The variability of time perception suggests that time may not be experienced uniformly by everyone, raising questions about its objectivity and how personal experiences can shape our understanding of temporal reality.