Studies have previously reported that the cool-tone glow of your phone screen, known as ‘blue light’, could be harmful for your sleep patterns. It has become such a common belief that phones and tablets these days, typically, have some version of a ‘night mode’ that tweaks the screen’s colour to warmer tones as you wind down for bed.
A new study conducted by researchers from the University of Manchester has found that the dreaded blue light may not actually affect your sleep and may actually help you wind down.
Sunrise and sunset naturally regulate humans’ sleep patterns, with light exposure determining how tired or alert you feel. Light is filtered through photo-receptors in the eye, including a specialised protein called melanopsin. When we wake up, melanopsin measures the brightness of daytime light and halts production of the sleep-inducing hormone melatonin.
Throughout the day, bright light keeps us awake, boosting attention and mood. As light dims in the evening, melanopsin triggers melatonin production, making us drowsy and helping us fall asleep.
For the study, mice were exposed to special lighting to see how cool- and warm-tone lights, of the same brightness, affected them. Surprisingly, results showed that blue-toned light had less of an effect on the mice than yellow-toned light, when it came to their internal clocks or circadian rhythm.
These findings have important implications for the design of lighting and visual displays intended to ensure healthy patterns of sleep and alertness. Current technologies are designed to limit our evening exposure to blue light, by changing the screen colour on mobile devices and may, therefore, send us mixed messages, the study argues.
Researchers suggest that, since twilight is dimmer as well as bluer than daylight, looking at warm-toned light at night could be sending our bodies mixed signals. Instead, using dim, cool lights at night and warm bright lights during the day might help our bodies on track. They believe that most night mode settings will dim the back-light; the noticeable change in colour could be doing us more harm than good.
“We argue that this is not the best approach, since the changes in colour may oppose any benefits obtained from reducing the brightness signals detected by melanopsin,” said Dr Timothy Brown, author of the study. “Our findings suggest that using dim, cooler, lights in the evening and bright warmer lights in the day may be more beneficial.”
Dr Brown believes that the common view being that blue light has the strongest effect on our body clock is misguided. “In fact, the blue colours that are associated with twilight have a weaker effect than white or yellow light of equivalent brightness,” he explained.
“There is lots of interest in altering the impact of light on the clock by adjusting the brightness signals detected by melanopsin but current approaches usually do this by changing the ratio of short and long wavelength light; this provides a small difference in brightness at the expense of perceptible changes in colour,” he further added.
The researchers firmly believe that this may not be the best approach, as the changes in colour may oppose any benefits obtained from reducing the brightness signals detected by melanopsin. Previous research has already provided evidence that aligning our body clock with our social and work schedules can be good for our health. Dr Brown seems to think that using colour appropriately can help us further achieve this.
