16 July 2021 · Mazda Stories

The Science Of Light

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The Evolution Of Light

Light influences our circadian rhythm – also known as a ‘body clock’ – which regulates our sleep-wake cycle, improves cognitive functions and increases activity levels. Utilising light in any human space is an area of expertise for environmental psychologist Dr Sally Augustin, who consults on creating environments people can thrive in, for both individuals and organisations. “Part of my job is really getting into how the physical world around you influences what goes on in your head,” she says.

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Human behaviour is affected by two elements of lighting – the intensity and colour temperature. Studies show that while cooler lights enhance concentration and alertness, warmer lights promote relaxation and comfort. Like many psychologists in her field, Dr Augustin believes that our responses to light date back to our experiences as a young species. “During sunrises and sunsets, the warm natural light would transition us gently from our sleep-wake cycle. But natural light becomes cooler during the day, which is when we needed to be productive.”

This influence over circadian rhythms is so well documented that it’s created the concept of human-centric lighting: the use of artificial lighting to mimic the course of natural daylight indoors. Many engineers, designers and architects have already harnessed human-centric lighting to successfully illuminate spaces and enhance human performance. It can even stimulate recovery in medical environments.

Lighting In Architecture

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Lighting In Architecture
Lighting In Architecture
Lighting In Architecture

To assist these industries, the International Commission on Illumination (CIE) has spent more than two decades defining a system that measures optical radiation (light) and its responses. These guidelines offer recommendations for appropriate lighting levels in any environment.

“Lighting is an important factor anywhere where humans are; it can be a vehicle, a school, a home or a hospital,” says Dr Tim Brown, a Professor of Neuroscience at the University of Manchester. His research on circadian rhythms has contributed significantly to the CIE’s measures. “Lighting designers, electrical engineers and architects can refer to this information so they know how much light and what wavelengths they should be abiding to, depending on the environment they’re designing for.”

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Mazda’s Lighting Study

The psychological and physical effects of light haven’t gone unnoticed in Hiroshima either. Kenta Kubo, Technical Leader of the Craftsmanship Development Group at Mazda, and his team conducted their own study of lighting and how it affects people’s behaviour and mood. “By understanding the characteristics of human perception, emotions and cognition, and incorporating this essence into the vehicles, we aim to deliver cars that activate the body and mind,” he explains.

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This concept of translating emotion into product design is called Kansei engineering, which Mazda has worked with for decades. The first steps towards Mazda’s Kansei engineering of light began following a conversation between Kubo and his colleagues Keiichiro Yamamoto and Danjoh Hiroki. They noted that the LED lights in different parts of a vehicle can be a variety of colours. This ‘visual noise’ can be distracting for vehicle occupants, so they wanted to understand how humans recognise visual input and colour temperature. Their study was conducted in a dark room and measured both brightness and chromaticity (colourfulness). “We wanted to know how each colour is perceived differently by the human eye,” says Kubo. “What surprised me the most was that there are so many different colours of white for humans.”

Once the study was complete, the team began to apply the results to the interior lights of the latest Mazda3, the Mazda CX-30 and the Mazda MX-30. The colour selected was white. “The human eye is extremely sensitive to the type of white Mazda wants to produce,” says Kubo. The team adjusted and unified the colour and brightness across the cabin’s controls and instrument panels. The important trip information the driver needs to know is the brightest, while the rest of the cabin’s light is toned down. As a result, the cabin space supports the driver’s field of vision by reducing visual noise, allowing the driver to feel relaxed but focused, even at night.