Studies have shown that correct night light helps sleep and mental well-being

Nowadays, the words “human-centered lighting”, “day and night lighting” and “biological lighting” are often seen in newspapers. In fact, no matter what the word is, it is nothing to say: proper dimming lighting can create for humans within 24 hours. The ideal condition.

And no light source can be "tunable" like an LED, providing a source of light at a specific color temperature, spectral power, color, and brightness. In short, people-centered lighting can inspire people's excitement in the morning and afternoon, and let them relax at night. It can be tuned to the same level as the sun, reinforcing millions of years of sunrise and sunset rhythms and 24-hour circadian rhythms.

If the designer can incorporate as much natural light as possible into the palette of LED colors, it will have a huge impact. We all know that stimulation and alertness can improve learning and efficiency, and relaxation can help sleep. Conversely, at the wrong time, the wrong light may ruin these things, and some researchers believe it will help produce cancer, diabetes and other diseases.

Dimmable, human-centered lighting (HCL) can be used anywhere, such as schools, offices, hospitals, homes, and more.

Human-centered lighting (HCL) is most effective in hospitals. Adjusting the LED to stimulate the blue frequency at certain times of the day, and warming the light at other times can help the patient sleep and heal. In the office, a well-designed lighting system can boost morale and productivity.

Mariana Figueiro, director of the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute, has always believed that in the office, the right night light can help employees sleep better at night and can help them cheer up.

Rensselaer Polytechnic Institute conducted a three-year study in five different buildings of the General Services Administration (GSA), and subsequently released a report with the GSA: "Office workers receive sufficient effective light or daylight in the morning, than those People in dim or low light have better sleep, depression and lower stress."

The study had 109 participants who used an electronic pendant designed by LRC to measure light intake, with the LRC metric "CS" ranging from 0.1 to 0.7. 0.7 represents the highest point of natural daylight.

Figueiro and members found that employees exposed to CS at least 0.3 in the morning “can fall asleep faster, with better sleep quality than employees with a CS of 0.15 or less.” Participants in the winter and in the summer for 7 consecutive days Wear this electronic pendant. The results show that when CS is 0.3 or higher, the sleep effect is better in winter and the same in summer. The decompression advantage is also consistent.

Figuero said: "I am not surprised by the results. This is what we are looking forward to. The light during the day is very important, and there is a lot of light at night, such as the glimmer of the night and the light of the mobile phone display, but we are indoors. The time is 80%-90%, and two-thirds of the time is in the office. People have not noticed the importance of office lighting, it can help you sleep better at night."

Figuero said that the study is only the "first stage" and her research has three stages. It is worth noting that the first phase did not involve dimming. Instead, it only measures the light that participants get from existing sources, including natural light and traditional fluorescent lights, not even LED light sources.

In the summer and fall of 2016, the “second phase” was carried out in two different places. The LRC installed LED panel lights behind the employee's computer screen and directed directly to approximately 40 participants.

Figure 1. The LRC installed an LED source in the study and adjusted the light to 0.3 CS to increase the excitement. Participants said they felt more awake and more energetic.

In the first phase, LRC scientists measured the effects of light on nighttime sleep, stress and depression, and scientists also documented the stimulatory effects. The hypothesis at the time was that when CS was 0.3, light would irritate the eyes and cause happiness, because when light hits the non-visual receptors (ipRGCs) of the retina, it stimulates a pigment called melanopsin.

The result of the second phase is: "By intervention, we found that the subjects reported that they would be more sleepy and energetic." "We collected data in the winter and we found that if we add a light that provides CS 0.3, It will increase their subjective feelings, reduce drowsiness, increase energy and vitality."

The third phase aims to further demonstrate the potential effectiveness of LED dimming for day and night alternation. Figuero believes that healthy lighting should be delivered in "layers" where ambient lighting can come from ceiling fixtures, while circadian rhythms can come from the blue frequencies of low lux that directly illuminate the eye. Although the light that shines directly into the eye sounds like a "fantasy", Figueiro points out that at 30 lx low light levels, Blu-ray still increases excitement, but does not cause annoying glare. She said: "If you do 470 nanometers, you only need 30 lx, so people think it is very comfortable." "You don't even see so much, because you have ambient light, and blue light has been integrated into it."

Although LED adjustability has great potential, Figueiro is also very clear that office designers must "hug" the sun.

Figueiro said: "One thing we learned is that the lighting design must be more sophisticated to provide the periodic stimulation we need. Daylight is the best stimuli, but it does not always enter the environment as it should. ."

If you don't have natural light all day in the office, try dimmable LEDs.

Figure 2. Casambi provides Bluetooth-controlled day and night lighting in different ways, such as through wall mounts, or through smartphones, tablets, and other applications that offer a wider range of color temperatures. These devices do not require a gateway.

Casambi CEO TImo Pakkala said: "The most important thing is color temperature control. When people talk about people-centered lighting, color temperature control is happening, but it is still early. We not only need new light sources, but also New control."

Although Casambi's controls are installed in thousands of locations in multiple countries, no more than 10% of these devices use adjustable CCT. But this percentage is growing, and the best place to go is a new building.

One of the places is the St. Vincent Square building on the 12th floor of Glasgow city centre. When the Registers of Scotland took over the 3rd floor, it adopted the HCL concept and used the Casam system to control approximately 300,300 square feet (300 square meters) of 300 LED lights.

The Registers of Scotland divides the LED ceiling lights into eight groups, with an open floor plan and 12 meeting rooms. Floor manager Kevin Stewart said that each group and room has its own iPad controller, which is installed in an open section that changes brightness and color temperature. (image 3)

Figure 3. The Scottish Registry's adjustable lighting is managed by the Casambi's iPad control mounted on the wall.

According to Stephen Jackson, business manager for Casambi UK and Ireland, the lights are pre-programmed to change color temperature throughout the day. In addition, iPad controls can change the background. Although the agency is really considering brightness, so far, there has not been much adjustment in terms of color temperature settings.

Therefore, for ordinary people in the office, even if the level changes subtly, the CCT will generally remain grayish throughout the day. The office's pantry can be set to a more relaxed amber tone, while the conference room can be switched to a cooler CCT.

The agency even installed some Philips "show" lighting that can change color, but it has not been used yet.