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How Blue Light Could Be Affecting You in Lockdown

Clocking hours of screen time indoors may be messing with your health

Social isolation has altered our lives in so many ways, but it turns out one of the most significant may be to do with light. “The challenge of social isolation is we’re sitting indoors. If you’re not getting enough light during the day and you’re getting too much light at night because you’re on your devices, it’s going to affect your biological clock, which is going to affect your sleep,” says Dr. Shadab Rahman, instructor of medicine at Harvard Medical School, associate neuroscientist at Brigham and Women’s Hospital and author of oft-cited research on light and sleep. “Sleep is an integral part of our physiology—without sleep, animals die; human beings also have a host of different diseases associated with sleep loss.”

Blue light specifically—present in device screens and LED bulbs, yes, but much more so in sunlight—impacts our biological clock more than other colours of the spectrum. The cells in the eye that act as receptors for blue light send signals through multiple regions in the brain that control many responses, “from your mood to heart rate, body temperature, hormone secretion, gene expression and stress response,” says Rahman.

“Ever been to Vegas, look down at your watch and not believe for a second it’s 3 a.m. because you feel 100 per cent? That’s blue light exposure at its best,” says Toronto sleep consultant Amanda Jewson. “Unfortunately for us, we have little Vegas at our fingertips with our phones, computers and tablets.” Devices with LED screens skew blue because blue light is much more energy-efficient. (Even if LED light bulbs are marketed as “warm,” they’re much more blue than incandescent lighting.)

But blue light is not the bogeyman it’s sometimes made out to be. “By no means are we to avoid blue light throughout the day,” says Rahman. It’s a question of timing, and intensity. As he explains it, a table lamp emits around 20 lux; your phone is 30-40 when you hold it about a foot from your face; indoor lighting is around 100. Usually, we don’t adjust those levels throughout the day and night. But our bodies want to take cues from natural lighting patterns outside. The sunlight on a cloudy day is around 1,000 lux, and if it’s sunny and clear-skied at midday, it could be 100,000. The light provided by nature in the hours before bedtime—moonlight—is around 1 lux.

Even if you avoid all devices at night, if you don’t get a good dose of natural light during the day, you could still have trouble sleeping.

“The whole problem is that we’ve lost the natural contrast of night and day using artificial lighting,” says Rahman. In fact, even if you dim the lights and avoid all devices at night, if you don’t go outside and get a good dose of natural light during the day, you could still have trouble sleeping.

The problem is not just that you might take a bit longer to fall asleep. It’s compounding. “If you get blue light right before bedtime, it’s going to tell your clock, ‘Hey, it’s still daytime, stay up later.’ It’s going to extend the length of your day and delay the programming of the clock, so the next day you would start feeling sleepy a little bit later,” explains Rahman. “It also makes you more alert. Together, that can make it hard to fall asleep, and you have a problem falling asleep tomorrow, and then the cycle perpetuates.”

Rahman’s research on shift workers has shown the damage caused by consistently staying up and working in artificial light when the body is signalling for sleep. “Mood disorders, obesity, diabetes, metabolic syndrome and high blood pressure are very prevalent in shift workers,” he says. This misalignment of light and sleep patterns can bring on a pre-diabetic state in young, healthy individuals, but when the pattern is fixed, that can be reversed in a couple of weeks.

If you’re worried about your late-night iPad usage, just be glad you’re not an astronaut. Rahman is researching optimal light intensity and colour characteristics for the International Space Station, where stakes are very high. He creates a 24-hour cycle of lighting to better match a natural pattern and tests its impact on the ground and then in space. “Astronauts are doing shift work and they’re sleep-deprived, and the risk of an accident there is so much greater—when you’re docking, if you’re off by a millimetre you can bring the whole station down,” he says. “Accidents do happen because of fatigue, so fatigue management programs up there are critical.”

“Screens are incredibly addictive and have been designed as such.”

To a (much) lesser extent, light-related fatigue affects all of us. Especially now, when many of us aren’t in a position to turn everything off at sunset. “Those who are still working from home are working even longer hours because now we have to take care of our family as well,” says Rahman, who has three kids at home. (The irony of writing this story on my laptop at 11 p.m. is not lost on me.) Plus, many of us don’t want to put down our devices when we’ve finished working. “Screens are incredibly addictive and have been designed as such, right down to the colours developers choose for their apps,” says Jewson. “Our brains become hardwired to get notifications and check what’s new—all the time.”

This is where blue light glasses can come into play. Many eyewear retailers in Canada now offer blue-blocking glasses made with either a coating on the lens, which reflects a blue hue and makes white appear more yellow, or a filter embedded in the lens that absorbs blue light and neutralizes it; this is less detectable and causes only slight discolouration. Eyewear chain Bonlook offers a blue-light filter as an add-on to most prescription glasses or alone for those who don’t usually wear them.
Bonlook national optician manager Rajbir Sidhu has seen an upswing in people asking about blue light filters, perhaps because the brand’s demographic is largely young professionals glued to their screens. “Someone who spends a lot of time in front of a computer is going to feel eye strain, soreness, irritation, sometimes a lack of focus,” says Sidhu. “We naturally blink less staring at screens.” He says blue-blocking lenses may help with these symptoms and suggests practicing the 20-20-20 rule: for every 20 minutes of screen time, take 20 seconds to look at a point 20 feet away.

“Just like you can’t have bright blue light all day into nighttime, you can’t be wearing blue-blockers 24/7.”

If you do invest in blue-blockers, Rahman has a message for you. “Just like you can’t have bright blue light all day into nighttime, you can’t be wearing blue-blockers 24/7. Wear them for the last couple of hours before bedtime if you want to, but also make sure the intensity of light is dimmed. If you have two lights on in your office during the day, turn one of them off; reposition your lamp so that it’s not facing you directly.”

You could also try programs such as F-lux that dim and warm screen light every evening, though “to date none of the studies that have been done on these programs have actually shown them to be effective,” Rahman says, because the light that emits can still activate your brain.

Jewson advises setting bedtime boundaries if you’re struggling with sleep. “There have been recommendations from scientists to remove all screen use 30 to 120 minutes before bedtime to reduce light exposure. Make sure your room light is low as well,” she says. “Find a good book and put your phone in another room so you’re not tempted to check it during the night.” If you are, just think of the astronauts.

 

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