Exposure to warmer colors might actually be worse for sleep than blue light, new study of mice finds

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Alex Heath / Tech Insider
  • The notion that blue light is worse for sleep patterns than warm light might be flawed, a new study suggests.
  • Researchers at the University of Manchester tested the impacts of blue light and yellow light on mice’s sleep patterns and found that blue light is less disruptive to sleep patterns than previously thought.
  • “Night mode” has seen a recent spike in popularity – the latest iPhone and Pixel operating systems both include beefed-up night mode options, with many third-party mobile apps offering night mode as well.
  • Visit Business Insider’s homepage for more stories.

“Night mode” features that shift phone or computer screens to warmer colors late at night are intended to help with sleep – but a new study suggests the science underlying that technology could be more complicated, The Guardian first reported.

Before now, common wisdom was that blue light was more disruptive to people’s circadian rhythm than warm colors – that was the thinking behind a slew of features recently rolled out for devices including the iPhone and iPad that automatically shift displays to an orange-yellow tint late at night. Some past studies have suggested that blue light suppresses melatonin, a hormone that influences sleep.

But the new study, published in Current Biology and led by Dr. Tim Brown, suggests that it’s more natural to look at blue light in the evening and warm light during the day. That may be because natural light is actually bluer during twilight.

“We show the common view that blue light has the strongest effect on the clock is misguided; in fact, the blue colors that are associated with twilight have a weaker effect than white or yellow light of equivalent brightness,” Brown said in a statement.

The team of researchers used specially designed lighting on mice in order to test how different wavelengths affected sleep patterns. Blue light proved less disruptive to mice’s sleep than yellow light of the same brightness, according to the researchers.

But the study was only carried out on mice, and its findings may not carry over to humans. Researchers noted that further studies are necessary to understand how human sleep patters are affected by different light wavelengths.

The researchers’ findings seem to reaffirm the common belief that lower brightness is less disruptive to sleep.

“Our findings suggest that using dim, cooler, lights in the evening and bright warmer lights in the day may be more beneficial,” Brown said.

Read the researchers’ findings here.