THE HIDDEN EFFECT: HOME LIGHTING AND CHEWING SPEED CAN DISRUPT OUR CIRCADIAN RHYTHM

Introduction

The human body is governed by a complex internal timing system that synchronizes the brain, gut and environment. While we often blame stress or poor diet for health issues, overlooked daily habits, such as exposure to artificial lighting at home like (LEDs) or the speed at which we chew our food, can quietly influence the gut–brain axis and disrupt our circadian rhythm. Modern lifestyles increasingly expose our bodies to misaligned signals, leaving our internal systems confused and conflicting 

Here lets Understand, how light exposure and eating behavior affect gut–brain communication reveals why often small habits can have long term consequences for sleep, metabolism and mental health.

The Gut-Brain Axis:

The Gut-Brain axis refers to the bidirectional communication network linking the gastrointestinal tract and the central nervous system. This communication occurs through neural pathways, particularly the vagus nerve and hormonal signals which involves different peptides and immune mechanisms are influenced by the gut microbes.

Nearly 90% of the body’s serotonin - a neurotransmitter involved in sleep is produced in the gut. The gut microbiota also modulates inflammation, stress responses and cognitive function. Indicating that digestion is not merely a mechanical process; it is deeply neurological.

When this communication is disturbed, the effects extend far beyond the gut, influencing anxiety, sleep patterns, appetite regulation and even decision-making.

Fig 1: Bidirectional brain–gut–microbiome interactions are regulated by neural, metabolic, and immune pathways and synchronized with circadian rhythms.

Circadian Rhythm and the Role of Light

Human Biological system lies the circadian rhythm, a roughly 24-hour cycle regulated by the brain’s suprachiasmatic nucleus (SCN) is referred as body’s master clock.

SCN relies on light which is the strongest environmental cue guiding this clock.

How Artificial lights alters the cycle ?

Darkness triggers the release of melatonin, the hormone which is responsible for sleep initiation and nighttime physiological repair. However, modern homes are built with artificial lights particularly blue-rich LED lighting from bulbs, televisions, and mobile screens.

Chronic exposure to light at night:

• Decreases melatonin secretion

• Delays sleep onset

• Alters glucose metabolism

• Disrupts gut microbial rhythms

Current researchers find that the gut bacteria themselves follow circadian patterns. When light exposure disrupts the brain clock, microbial rhythms also become desynchronized, changing the digestion and immune balance.

How the Gut manages the Time period?

The gut not only need to responsive to the brain clock but also to its own peripheral clocks which is embedded in the intestinal walls, they regulate

• Nutrient absorption

• Gut motility

• Barrier integrity

• Immune responses

Any irregular exposure of light not only changes the central clock but also the gut which leads to chronic health issues like GI dis functioning

Why Chewing matters…

In today’s lifestyle, eating quickly has become normalized and also we are distracted to many other entertainment rather than prioritizing our own health. Slow chewing helps mainly

• Improves satiety hormone release (GLP-1, leptin)

• Reduces ghrelin (hunger hormone)

• Promotes efficient digestion

  
  

When food reaches faster than the brain can register fullness, it can promote overeating and impair digestion. So current trend late night cravings will completely disrupt this cycle and cardiac rhythms and can lead to chronic fatigue, weight gain and many more lifestyle chronic diseases.

Health Implications

• Insomnia and poor sleep quality

• Anxiety and depressive symptoms

• Obesity and insulin resistance

• Irritable bowel syndrome (IBS)

• Chronic inflammation

Habits to reconnect with our Rhythm

• Using warm, dim lighting after sunset

• Avoiding screens at least one hour before bed

• Eating meals during daylight hours

• Chewing each bite slowly (20–30 times)

• Maintaining consistent meal and sleep schedules

Conclusion

The gut and brain are constantly listening to light, to food and to behavior. In a lifestyle  that no longer matches our biology, awareness becomes a powerful tool to be followed . By respecting natural light, dark cycles and practicing mindful eating, we can restore harmony to our internal clocks and support long-term physical and mental well-being.

About the Author:

Anjana G

Biotech Undergraduate

References

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Image Reference

1. Frank J, Gupta A, Osadchiy V, Mayer EA. Brain–gut–microbiome interactions and intermittent fasting in obesity. Nutrients. 2021 Feb 10;13(2):584.