Blue Light May Not Actually Disrupt Sleep, Study Finds

Staring at the cool-toned glow of your phone screen, known as “blue light,” at night is harmful to your sleep patterns, right? It’s such a common belief that phones these days typically have some version of a “night mode” that tweaks the screen’s color to warmer tones as you wind down for bed. But a new study from the University of Manchester found that the dreaded blue light may not actually mess with your sleep—in fact, it may help you wind down.

The study, published in Current Biology, used special lighting to see how cool and warm-toned lights of the same brightness affected mice. As it turns out, the blue-toned light had less of an effect on the mice than the yellow-toned light when it came to their internal clocks, or circadian rhythm. Again, both lights were equally bright.

It may sound surprising, but the scientists suggest that since twilight is both dimmer and bluer than daylight, looking at warm-toned light at night could be sending our bodies mixed signals. Instead, they think using dim, cool lights at night and warm, bright lights during the day might help keep our bodies on track. Although most night mode settings will dim the backlight, the noticeable change in color could be doing more harm than good. 

“We argue that this is not the best approach, since the changes in color may oppose any benefits obtained from reducing the brightness signals detected by melanopsin,” study author Timothy Brown, PhD, said in a release. “Our findings suggest that using dim, cooler, lights in the evening and bright warmer lights in the day may be more beneficial.”

So basically, it might be better to do the opposite of what you’ve been doing since the dawn of night mode. That said, this study looked at how the color of light, not the presence of light itself, affected sleep.   

“Research has already provided evidence that aligning our body clocks with our social and work schedules can be good for our health,” Brown said. “Using color appropriately could be a way to help us better achieve that.”