The effect of blue LED on melatonin

On December 19, 2023, the joint team of Korea National University and Samsung Electronics developed and designed a human lighting product that regulates the secretion of human melatonin by combining different wavelengths of blue LED, promoting sleep and keeping awake. The results have been published in the journal ACS Omega.

The research team said that over thousands of years of evolution, humans have developed a day-night habit of working in the white, sunset, and relying on the sun to regulate our sleep/wake cycle. But today, many people spend most of their time indoors, away from sunlight, making it difficult to maintain an optimal 24-hour circadian rhythm. And exposure to artificial light can worsen the problem of irregular circadian rhythms, because artificial light can lead to a decrease in melatonin secretion, especially at night exposure to blue light, which can interfere with melatonin production and thus affect sleep.

Blue light is usually emitted by LED light sources in lights, computers, televisions, mobile phones and other electronic devices that people use at night. Therefore, in order to reduce the negative impact of blue light on human rhythms, the joint team of Kookmin University and Samsung Electronics has created an LED blue light source that can simulate natural circadian rhythms.

According to the research team, the wavelength of blue light ranges from 380 to 500nm. The wavelengths that inhibit melatonin production and induce wakefulness are in the range of 460 to 500nm. So the researchers designed two leds with different wavelengths of blue light. Among them, the blue LED used during the day is limited to a wavelength close to 475nm; Blue leds used at night, with wavelengths approaching 450nm, are outside the range of wavelengths that interfere with sleep.

After that, the researchers combined the two new leds to create an LED human lighting bulb and began a comparative test experiment. In the experiment, the new LED human lighting bulb was placed in a windowless room with the traditional LED bulb, and the experimental volunteers lived in the room for three days. The researchers measured melatonin levels in the volunteers.

In the end, saliva samples from the 22 volunteers showed that compared with the volunteers who were continuously exposed to traditional LED lights, the volunteers under LED human lighting bulbs had a 12.2% increase in nighttime melatonin levels and a 21.9% decrease in daytime melatonin levels.

The research team hopes that LED lamp and display manufacturers can apply this new invention to help people improve their vitality and work efficiency during the day, while improving the quality of relaxation and sleep at night.