Part 3 ~Daily light cycle~

Our daily life is greatly influenced by the daily light cycle.
They tend to wake up at sunrise, be active when the sun is high in the sky, and relax at dusk.

Natural light cycles affect your sleep rules, mood, and even your health.
While natural light can energize, improve focus, and provide peace of mind, it is also known to disrupt sleep.
Natural light is important for regulating our internal body clock and controlling our body's functions and sleep-wake cycles.

On the other hand, dark light or lack of light is also known to have various effects on human health.
Lack of natural light can negatively impact the quality and quantity of your sleep.
It affects the reset of the body's internal clock and the secretion of melatonin (sleep hormone), which can disrupt the sleep regulation mechanism.

This time, we will explore the effects of the daily light cycle on our bodies and minds, as well as tips for improving the quality of our daily lives.

What is the body clock?

Are you familiar with the term "body clock"?
Our bodies have a function called a biological clock.
The body clock plays a role in regulating our daily rhythms and physical changes.
This mechanism is controlled by the SCN (suprachiasmatic nucleus), a part of the brain.

The SCN senses the solar cycle and changes in light and darkness, and adjusts our body clock according to sunlight.
The biological clock has the role of transmitting time information to other cells and tissues.
The body clock works with each part of our body to maintain a balanced biological rhythm.

What effect does light have on the body clock?

Our body clock is very sensitive to changes in light and adjusts our daily rhythms.

The body clock senses light stimulation through the SCN, which is located in a part of the brain, and receives light information from the outside through the optic nerve located at the back of the eyes.
In particular, when a strong amount of light reaches the SCN, it acts as a signal to reset the body clock.
The cycle of the sun and changes in light and darkness are very important for resetting this body clock.
By being exposed to bright light in the morning, your body clock senses that it's morning and switches to an active state.
On the other hand, by being in a dark environment at night, the body clock senses that it is night and adjusts to the time for rest and sleep.

The body clock uses the effects of light to regulate our daily rhythms and adjust the timing of our sleep and meals.
Light stimulation also affects the activity of genes in the body's internal clock, which also plays a role in controlling the cycles of protein production and degradation.

Recent research has attempted to use artificial light to adjust the body's internal clock and improve sleep disorders.
For example, light therapy uses specific wavelengths or light intensities to help you wake up smoothly in the morning, or light control to help you sleep naturally at night.

Light is an essential element for our internal body clock and for maintaining a healthy rhythm.
Proper use of light is key to improving sleep and activity quality, promoting health and well-being.

How is the body clock adjusted?

The body clock operates on a 24-hour cycle, regulating physiological processes such as sleep-wake cycles, hormone secretion, and body temperature.
This internal clock is adjusted by external factors such as light and meal timing.

Adjustment of the body clock involves various factors such as sleep and diet.
Melatonin, known as the sleep hormone, is an important hormone that regulates the rhythm of the body's internal clock, and its secretion normally increases at night, promoting the sleep cycle.

Moderate exercise and exposure to bright light during the day are also effective in adjusting your body clock.
It is known that exercising at the right time activates your body clock and increases your daytime activity.

Diet is also an important factor that directly affects your body clock.
The body clock regulates appetite and metabolism, especially through mealtimes.
For example, it is known that eating breakfast resets the body's internal clock and switches to a state of alertness.
Eating a large meal late at night can also reduce the quality of your sleep as your body clock interferes with the digestion of your food.

There are a wide variety of factors involved in adjusting the body clock, but sleep and diet are particularly important factors.
By properly adjusting these factors, you can maintain a healthy lifestyle and support the adjustment of your body clock.

The rhythm of the day brought about by natural light

Our bodies maintain a natural rhythmic harmony with the ever-changing light of morning, day, and night.
Therefore, harmony between natural light and the rhythm of the day is essential for our lives.
In order to live a healthy and balanced life, it is very important to consciously incorporate natural light.

Morning light and the rhythm of waking up

The morning light and the rhythm of waking up have a profound impact on our daily lives.
The latest research shows that morning light adjusts our body clock and has a significant impact on the quality of our awakening.

Morning light plays an important role in resetting your body clock.
In particular, short wavelength light called blue light, which is also found in sunlight, promotes wakefulness and sends signals that regulate body temperature and hormone secretion.
This allows your body clock to work accurately and maintain your morning rhythm.

Morning light also has psychological effects.
Bright light stimulates the secretion of a neurotransmitter called serotonin, which has the effect of elevating your mood.
This is said to improve your concentration and productivity after you wake up.

Morning light and the rhythm of waking up are closely related to our health and sense of well-being.
This is why it is important to bathe in the morning sun in order to wake up with a natural rhythm.

Increased daylight and performance

New research shows that daylight has a significant impact on our performance.
Bright natural light is thought to improve focus, attention, creativity, and productivity.

Sunlight resets your body clock and helps you wake up. In particular, light at a wavelength called blue light is an important signal that supports wakefulness.
This light effect makes us more alert and helps us concentrate on our work.

Sunlight also has psychological effects. Bright light stimulates the secretion of a neurotransmitter called serotonin, which has the effect of improving mood.
This can be expected to increase positive thinking and creativity, leading to better work results.

However, in modern office environments, artificial light is the mainstream, reducing opportunities for exposure to sunlight.
This can lead to decreased concentration and increased stress.
Therefore, it is necessary to incorporate artificial light that is similar to sunlight.

Place your seat near the window in your office to benefit from sunlight and improve performance.
Effective measures include creating a space that lets in natural light and going outside to soak up the sun during breaks.
You should also consider choosing artificial lighting that is closer to sunlight and adjusting blue light.
Sunlight is the key to improving our performance and achieving a more fulfilling workday.

night light and quality sleep

The human body clock is adjusted by changes in light.
However, in modern life, it is common to use bright lights and devices even at night.
This can disrupt your body clock and affect your sleep.

Blue light in particular has been shown to have the potential to interfere with sleep.
It suppresses the secretion of the hormone melatonin in the brain and promotes wakefulness, which can make it difficult to fall asleep.
It has also been suggested that bright light at night can reduce the depth and soundness of sleep.

In order to achieve high quality sleep, it is necessary to review the light environment at night.
It's important to use blinds or curtains in the bedroom to create darkness and limit the use of electronic devices before bed.
Additionally, it is also effective to use screen filters and blue light blocking glasses to cut out the blue light from your devices.

Adjust your body clock through light

The daily light cycle has a major impact on adjusting our body clock and maintaining our health.
Exposure to natural light properly resets the body's internal clock, regulating the sleep-wake cycle and hormone secretion.

In order to maintain a suitable light environment, it is important to let in natural light during the day.
Encourage relaxation and harmony in your mind and body by going outside and soaking up the sun and spending time under natural light.
On the other hand, it is important to create a dark environment at night.
Limit your lighting and use of digital devices, and try to avoid light stimulation to improve your sleep quality.

Disruption of the body's internal clock due to lack of light or irregular light cycles can have negative effects on health.
Sleep disorders and physical and mental disorders may occur, but this can be improved by paying attention to creating an appropriate light environment and adjusting your daily rhythm.

Adjusting your body clock through light is an important element in supporting a healthy life.
By actively incorporating natural light and creating an appropriate light environment, you can maintain harmony and health in your mind and body.




Written by: BARREL Editorial Department
Supervised by: Yuki Oe (Lecturer, Department of Lifestyle Design, Faculty of Human Culture, University of Shiga Prefecture)
Lecturer at the University of Shiga Prefecture, Faculty of Human Culture (Department of Lifestyle Design).
She specializes in architectural environments, light environments, lighting environments, and color environments.
She is a member of the Architectural Institute of Japan/Illumination Institute of Japan.
After completing her doctoral course at Nara Women's University Graduate School of Humanities, she worked in technology planning at Sharp.
She worked as an assistant professor in the Faculty of Science and Technology at Tokyo University of Science and as a part-time lecturer at Osaka Jonan Women's Junior College before reaching her current position.