Episode 20 – Is blue light at night really that bad?

What is all this fuss about blue light? You’ve probably heard about it having something to do with the backlighting on your smartphone or other electronic device. But what actually is blue light? What’s it doing to your brain? Is it really that bad? In episode 20, Aleena and Janine are keen to see what the science says. They also have the final installment of the ever-popular segment: How’s Aleena’s Kitchen Renovation Going?!; Janine’s holiday nerdery; plus gushing over Björk’s new album AND podcast! OMG!

Mastering of this episode, plus intro and outro music, by the ever-talented Dr Adrian Diery.

First things first: here’s what you need to know abuot circadian rhythms and melatonin

Effects of night-time smartphone use with or without blue light

When participants were exposed to blue light-emitting smartphones they were significantly less sleepy and less fatigued after smartphone use, and they performed significantly worse on cognitive performance tests, as compared to when participants were not exposed to blue light. When exposed to blue light, participants also had lower melatonin levels, a delayed onset for melatonin release, and higher body temperatures, but these differences were not found to be statistically significant. The authors describe the findings as clinically significant and suggest suppression of blue light at night.

Does blocking blue light at night reduce insomnia?

In this randomised controlled trial, 14 men and women who had diagnosed insomnia wore amber blue light blocking lenses for two hours before bedtime (and during any night-time awakenings) for one week. Each participant also wore clear placebo lenses for a week: yep, this was another crossover design where participants do both experimental conditions and “act as their own control”.

When wearing the blue light blocking lenses, participants’ insomnia was significantly reduced. They also said that they slept longer and had better quality and soundness of sleep. Measures of sleep time from accelerometers (kind of like the fitness device you might wear on your wrist), also reported that participants slept longer. Sounds dreamy!

This was a small study and, since the researchers didn’t measure melatonin, we can’t be sure that insomnia was reduced because the blue light blocking lenses helped to normalise participants’ evening melatonin levels. Cue more research please. But this is a plausible explanation that fits with what we know about how blue lights effects circadian rhythms.

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Photo by Egor Vikhrev on Unsplash

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