The blue light from your phone isn't ruining your sleep

For a decade, we've been told our screens are wrecking our sleep. The real culprit is far bigger than the glow from your phone.

I have spent the last few weeks strapping on a pair of special orange safety goggles three hours before bed. They're made of thick, uncomfortable plastic that casts the world in a dull amber glow, making it hard to see anything blue. But I don't stop there. I cover the windows with blackout curtains and switch off all my lamps, one by one. In their place, I exclusively light my apartment with candles. My sleep routine is deranged, but it's for an experiment. I found out what happens when you banish blue light.

The world has grown increasingly panicked about this photochromatic fiend over the past 10 years. We're told that our phones, TVs, computers, tablets and LED light bulbs expose us to a perverse amount of blue light. Supposedly, this ruins our sleep by disrupting the natural rhythms of daylight that influence our internal body clock. There's science to back some of this up, but recent studies and analysis suggests that things are a lot more complicated. In fact, chances are good that you've fallen for some serious misconceptions on this subject. Experts tell me it's unlikely that light from your phone is ruining your sleep.

The research is mixed. Those features designed to dial down blue light on your phone at bedtime, for example, are probably doing very little to improve your sleep. But the lighting of modern life really can have a huge effect on your sleep. What would it take to make a change?

I wanted the truth. So, I called the experts and dove into the science.

And to see if I could spot the difference, I've plunged myself into the most extreme, blue-free evenings I could muster. I landed on practical advice that you can use – no dorky tinted goggles required. It could be the secret to a good night's sleep.

The blue screen of death?

The public freakout about blue light started with a study in 2014. Half of the 12 participants read on an iPad before bed. The rest read physical books. The iPad users took longer to fall asleep, felt groggier the next day and produced less melatonin. The researchers said the culprit was the glow emitted from the iPad's LED screen, which produces a disproportionate amount of light in the upper, bluer end of the spectrum. Under specific circumstances, blue-enriched light disrupts the daily circadian rhythm – our body's natural pacemaker – that uses daylight to help determine when we start to feel tired. Subsequent research seemed to support the findings. Sounds simple, right? It's not.

"This was an incredibly deceptive piece of work," says Jamie Zeitzer, a professor of psychiatry and behavioural sciences at Stanford University, who studies the effect of light on the circadian system. The science wasn't bad, he says, the problem is it brought people to bad conclusions.

It's true that our screens are bluer. Modern screens and lightbulbs use LEDs, which cannot produce pure white light. Instead, they use blue LEDs and cover some of them with a chemical called yellow phosphor. The blue and yellow mix together and trick your brain into seeing white, but extra blue always leaks out. 

And blue light really can influence your sleep. Zeitzer says that's mostly because you have a light-sensitive protein in your eyes called melanopsin which plays a key role in your sleep system. "And melanopsin is a blue sensitive protein, which basically means that it is most sensitive to blue light," he says. Melanopsin reacts to other colours of light too, the effect of blue is just a bit stronger. 

"But the amount of light emitted from our screens is really inconsequential," says Zeitzer. Your life doesn't match the conditions of many blue light studies. "We bring someone into the laboratory, and they are exposed to very dim light all day long. And then they are given a bright light stimulus," he says. Under those circumstances, blue........

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