Don’t indulge in empty shouting”People-oriented design”, Melanopsin illumination (EML) to understand?
We have all learned basic knowledge about light color: low color temperature makes people feel comfortable and warm, and high color temperature makes people sober and excited.
▲ photos from gel-usa.com
Obviously, designers will use a higher color temperature in the office and a lower color temperature in the bedroom. This is a “people-oriented” design.
Why does it make us feel comfortable with the low light and warm ocean light? This leads to the next key word:
Humans have never been nocturnal organisms. Gathering of hunting for 180,000 years and arable land for 20,000 years have given rise to a pattern of working during the day and sleeping at night.
The pineal gland of the human brain secretes a hormone: melatonin, which is a “natural sleeping pill” and a spontaneous “rest signal” of our body. When there is a high content of melatonin in the body, we are lethargic; when there is a low content of melatonin, it will be sober.
The amount of melatonin is related to the strength of light. The eye senses the brightness of the environment and transmits the signal to the pineal gland to control the secretion of melatonin: more in the dark and less in the strong light. This is why people are more likely to fall asleep in the dark.
The intraocular melanopretinal retinal ganglion cells (ipRGCs) sense the intensity of the light and transmit the signal to the pineal gland.
▲ The photoreceptor cells of melanopsin are most sensitive to the light of blue wavelengths, and the blue light of 450-470 nm is the most effective to inhibit the secretion of melatonin.
The “artificial lighting” of the ancestors was only a fire light. The following figure shows the spectrum of the fire light: the color temperature is 2000K, and there are few blue lights and many red lights. This low-colored, warm ocean light makes people feel comfortable and accelerates to sleep.
In the work environment, high color temperature light with more blue components can prevent daytime sleepiness. Before work, less warm blue light with blue light causes the brain to send signals “reduce energy consumption and prepare for rest”, relaxing and sleeping at night. will be better.
- Let’s review a few knowledge points first:
1. People need different lights under different needs;
2, white light is sober and excited, yellow light is relaxing and comfortable;
3. The essence behind is the secretion of melatonin, a “natural sleeping pill”;
4. Blue light stimulates “photoreceptor cells of melanoma” and inhibits the secretion of melatonin.
These are qualitative analyses, and you may have heard of them. This is also the physiological basis of the recently popular “Human Centric Lighting” (HCL).
Below, we will further explain:
How to quantify the effect of light on our circadian rhythm? This leads to the third keyword in the title:
- Melanopsin illuminance
Before the invention of the artificial light source, sunlight was the only light source, and the ancestors “made it at sunrise and entered the sun.” With the widespread use of artificial light sources, people have a rich night life, and night lighting provides the wrong time signal, which has become an increasingly serious problem affecting human health.
▲Many people in modern times “have no day”. Compared with their ancestors, they lack light during the day and have too much light at night. (The chart is translated from atelier ten)
The ladder of biological evolution was measured in the hundreds of thousands of years, and the history of human civilization was less than 10,000 years old. Human beings have entered modern ways in terms of “software” such as psychology and culture, but the “hardware” evolution of physiological structures is far from changing. The “biological clock” in our body is such a “hardware” facility that cannot keep up with changes. The disturbance of the biological clock directly leads to sleep problems and can also lead to deterioration of emotions, and can also cause metabolic diseases such as obesity and diabetes.
But now it is impossible to limit nighttime lighting, so we should think more about: What kind of lighting system will not cause the disturbance of the biological clock?
▲Choose a higher color temperature during the day and gradually reduce the color temperature as you approach work
▲ Bedroom night light, toilet lighting, use low-light warm light to avoid unnecessary wake-up (picture from hammacher)
We hope to design a lighting system that provides enough stimulation during the day to allow us to stay awake. Illumination at night can meet the visual needs, but it does not inhibit the secretion of melatonin and does not affect the quality of sleep.