Part 1: What is good light? ~

Nowadays, it's trendy to incorporate plants into your home, whether you go out on the town or go into a store.
However, if you look at the plants that are actually placed here and there, you may find that their leaves are not very healthy or that they are being grown in an environment with no light.
Lack of light is of course the reason why plants are not doing well, but that is not the only reason.
In fact, there are "good light" and "bad light" in light.

Light plays a very important role not only in plants but also in the survival of humans.
Humans use light not only to see things, but also to gain peace of mind and a sense of happiness.
However, it is also true that the definition of good light varies depending on the person and the conditions.

In this column, I would like to think with you about the reasons why people accept light as good light and the effects light has on us.


Good light from six perspectives

Good light can be thought of from six broad perspectives: ``physiology,'' ``psychology,'' ``environment,'' ``culture,'' and ``activity.''
This time, I will first explain good light from the two perspectives of ``physiology'' and ``psychology.''

What is physiologically good light?

From a physiological perspective, good light refers to light that does not overstimulate the human visual system and has a healthy effect.
Providing just the right amount of light, neither too strong nor too weak, will help create a good light environment.

Sunlight contains many colors, but blue light in particular has a shorter wavelength than other colored lights and is said to have the effect of increasing alertness and attention.
However, too much blue light can also be harmful to your eye health.

The color temperature of the light is also an important factor; warm light can have a relaxing effect and induce sleepiness.
On the other hand, light with a cool color temperature is said to have the effect of waking you up and increasing your vitality.

Light contrast is also important.
Adequate contrast improves visibility.
On the other hand, excessive contrast can cause eye fatigue and stress, so mild contrast is preferable.

In this way, light with moderate brightness, a natural spectrum, a color temperature that matches the living environment, and appropriate contrast is considered good light.
Light that combines these elements is expected to be visually comfortable, reduce eye fatigue and stress, and increase concentration and productivity.

What is psychologically good light?

Light also has a huge impact on our mood and emotions.

From a psychological perspective, good light refers to light that has a positive impact on people's feelings and mental state.
Because light has a direct impact on our emotions and cognition, the right lighting environment is a key factor in our psychological health and well-being.

soft light

For example, everyone feels comfortable and secure in warm, soft light.
At night, when you want to relax, you might relax under dim lights.
Soft light gives a feeling of gentleness and peace, and is said to have the effect of reducing tension and stress.

On the other hand, cold colored or strong light can bring out vibrancy and creativity.
When you wake up in the morning, the mood you feel when you wake up will be different depending on whether the sky is clear and bright or the sky is overcast and rainy.
Also, sharp light and strong shadows can cause anxiety and tension.

In this way, the definition of good light differs depending on a person's psychological state.

Harmony of brightness and color

It is necessary to harmonize the light in order to give it psychologically good light.
Harmony of light is achieved by adjusting the balance of light and dark and color temperature.
Light with the right amount of brightness and natural colors can bring relaxation and comfort, and can improve mental stability and concentration.
On the contrary, excessive brightness or harsh shades can disrupt the harmony and cause stress and discomfort.

uniform light
An even distribution of light creates a sense of harmony and stability, and can be more calming than uneven light.
When light is spread evenly and covers the entire room, people tend to feel safe.
For example, when working or studying, an environment with uneven lighting reduces visual fatigue and confusion and promotes psychological stability.

fluctuation and movement

Fluctuations and movements of light also affect psychological factors.
Slow changes like natural light and subtle movements can help you relax and stimulate creativity.
On the other hand, sudden changes or flashing lights can cause anxiety and stress.
The fluctuation and movement of light has an impact on psychological comfort, so with the spread of LEDs in recent years, research and development into adjusting the fluctuation and movement of light is progressing.

Good light that promotes harmony between mind and spirit

Good light can be said to be light with harmony of brightness, softness and uniformity, and appropriate modulation and movement.
A light environment that combines these elements has a positive impact on physical and mental health.
A comfortable light environment is essential for maintaining the rhythm of life, as it has a relaxing effect, promotes concentration, reduces stress, and improves mental stability.
From a physiological and psychological perspective, good light can be said to be an important element that promotes harmony between our bodies and minds and fosters health and mental stability.



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.