Night mode blocking the phone’s blue light does not help sleep well


Over the past few years, scientists have claimed that blue light emitted from the screens of many electronic devices can significantly disrupt sleep.

To prevent this, most laptops or smartphones today have developed a setting called night mode to reduce blue light emissions.

A new study published in the journal Sleep Health, night mode trials found they have no effect on overall sleep outcomes, and the only way to improve sleep is to stop working altogether. exposure and use of electronic screens before going to bed.

Several decades ago, scientists discovered that a light-sensitive retinal protein called melanopsin is produced by small retinal cells in the back of the eye. Melanopsin is made in response to light and it helps regulate circadian rhythms, keeping the brain alert and alert.

Melanopsin has also been found to be particularly sensitive to the blue light spectrum, located around a wavelength of 480 nanometers. This underpins many theories that using LED screens and smartphones before bed can disrupt sleep.

So to reinforce consumer confidence, most smartphone manufacturers have designed a night mode, which adds warmer colors to screens in the evening. On an iPhone, this is called Night Shift, Pixel phones call it Night Light, and Samsung is the Blue Light Filter setting. But do these night modes really bring any measurable improvement in sleep results?

A team of researchers from Brigham Young University and Cincinnati Children’s Hospital Medical Center sought to answer that very question. Researchers recruited 167 young participants and divided them into 3 groups to conduct a 7-night study. One group was asked to spend an hour before bedtime using an iPhone with Night Shift enabled. The second group did the same, but turned off night mode. Meanwhile, the third group did not use the phone at all within an hour before going to bed.

Instead of turning on night mode, stopping all electronic devices before going to bed really helps us to sleep well.

Sleep quality is tracked using a wrist accelerometer, and multiple results are calculated, including bedtime, total sleep time, and the frequency of waking up during sleep. “In the whole sample, there was no difference between the three groups,” says Chad Jensen, the project’s researcher. Night mode is not superior to using the phone without turning on Night Shift, not even using a phone at all.

Going into the data, the researchers divided the cohort into two groups – those who slept an average of 7 hours per night and those who slept less than 6 hours per night. In the second group, the more chronically sleep deprived group, again no difference in sleep outcomes was found between all three groups.

“This shows that when people are too tired, people will fall asleep no matter what they did before they went to bed. Too much sleep pressure really doesn’t affect what happens before bed, ”Jensen said.

In the group that slept around 7 hours per night, researchers found some very small improvements in sleep quality in subjects who did not use the phone before bed.

These results indicate that blue light plays little or no role in a person’s sleeping rate or quality, Jensen said. Instead, the mentality involved in smartphone use is a much more powerful factor in altering a person’s sleep quality. “Although there is more evidence that blue light increases alertness and makes it harder to fall asleep, it’s important to think about which part of that stimulation is light emission,” Jensen said. with other cognitive and psychological stimuli ”.

This new study is not the first to show that common blue light filters for LED displays can be harmful. A 2019 study from the University of Manchester found that the perceived color of light can be very important in regulating human biological systems.

That study argued that the yellow light spectrum used in the night mode setting could be counterproductive, regulating melanopsin activity in ways that actually make the body think it’s daytime.

There’s certainly not enough evidence to suggest that the phone’s night mode is doing the opposite of what the manufacturer wants, or a study shows how blue light wavelengths affect the biometric regulation. learning in the human brain.

But this new study did give some of the first experimental evidence that a phone’s night mode might not help people get a lot of sleep. If you really want to improve your sleep quality, it’s best not to use your electronic device before bed.

Huong Giang (Source: New Atlas)

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