Research shows that “night mode” that turns the screen yellowing affects sleep more than blue light and disrupts circadian rhythms

A study suggests that “Night Mode” (night mode), which turns the device’s screen yellow, can backfire, affecting sleep like blue light and disrupting circadian rhythms. In recent years, mobile phone manufacturers and consumers have reached a consensus: blue light inhibits melatonin secretion, making the brain alert and not sleepy. The blue light emitted by mobile phones and tablets changes the circadian rhythm sanatorify the brain, negatively affecting sleep quality.

Photo by University of Manchester

To reduce the impact of blue light on us, most smartphones are now equipped with night mode, offering yellow or sepia heating filters designed to filter out the problematic blue spectrum. But now a new study from the University of Manchester questions the consensus, arguing that this warm color also affects the biological clock, and that studies of animals show that exposure to yellow light at night can also cause confusion.

In the human eye, there are a small number of light-sensitive cells in addition to the cone cells and round cells. The purpose of these cells is not to help us see light, but to sense it as part of our circadian rhythm management system. When these particular retinal cells sense light, they produce a molecule called melanin that tells us directly that certain parts of the brain remain awake and alert. In addition to suppressing melatonin, melanin has been found to help regulate and regulate the body’s circadian rhythms.

The current popular blue light hypothesis comes from a study that shows that blue light inhibits melatonin secretion, making the brain alert and not sleepy. In particular, the wavelength of 446-477 nanometers of blue light, the human melatonin secretion of the most inhibition effect. Scientists at Harvard Medical School in the United States asked volunteers to read paper books or iPads for four hours a night for two weeks.

It turned out that volunteers who watched the iPad at night fell asleep slowly, became sleepless, had poor sleep quality (shorter and delayed fast eye movement), reduced melatonin secretion, delayed circadian circadian clocks, and were prone to sleep the next morning.

This is because phones, tablets and other 452 nanometers rich in blue light, change the brain’s circadian rhythm, which has a negative impact on sleep quality. The paper book is a reflection of external light, belongs to the broad spectrum of white light, peak at 612 nanometers, there will be no such negative effects.

So if you want to use your phone, iPad, computer, and don’t want to affect sleep quality before you go to bed, you need to turn off the lights, set the screen to a minimum, or turn on the lights, and wear blue-light filter glasses.

Tim Brown, co-author of the new study, explained: “There is a lot of research to influence the biological clock by detecting the melanopsin to adjust the brightness signal, but most of the current research has been done by changing the ratio of short wavelengthtors to long wavelengths of light. This provides a small difference at the expense of small changes in brightness. We don’t think this is the best approach, because color changes may conflict with any benefit of reducing the brightness signal detected by the black vision protein. “

To study the specific effects of color on circadian rhythm systems, the researchers conducted a series of experiments on mice with altered taper sensitivity. The study used multi-color lighting technology to find that yellow light has a greater impact on biological bell behavior in animals than blue light.

The researchers continue to hypothesize that this color-related innate circadian rhythm relationship may be related to the actual shift of light within any 24 hours. The researchers speculate that in our biological clock, the natural shift to blue light along with sunset is related.

“Our evidence suggests that the industry consensus that blue light has a wrong effect on the biological clock, and in fact, it affects the biological clock less than white and yellow light at the same brightness, ” says Mr Brown. “

The new study was published in the journal Current Biology.

Source: University of Manchester

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