In the digital age, blue light is everywhere, and not just from the LED backlighting you get from hunching over your phone or laptop (yes, we do it too). Overusing screens isn’t the wisest thing for your eyes for a number of reasons, but there is a lot of confusion surrounding the impact of blue light.
Blue light isn’t all bad. It can increase attention, alertness, and improve wakefulness. Since before the invention of smartphones, it has been commonly utilised as an energy-efficient artificial light source, like the GE Link. But blue light can become a problem depending on how intense it is, how frequent it is, what kind of blue light it is, and — crucially — when we are exposed to it.
When the weather is moody, being inside a warm, well-lit building can lift you out of that autumnal slump. Things get pretty hairy, however, at night time. Here’s a brief rundown of why you need to avoid blue light towards the end of the evening, and especially if you wake up in the night.
Blocking blue light promotes better sleep
All light is bad news for melatonin — the neurochemical that makes us ready to go to bed, and keeps us from getting up in the morning.
However, a recent study from Harvard Health emphasises that blue light, especially at higher wavelengths, is the most forceful suppressor of melatonin, which is normally kept at bay during the day according to our body clock, or, if you want the fancy term, the circadian rhythm. The shorter wavelength of blue light in particular subdues the release of melatonin for double the length of time as green light wavelengths, and disrupts circadian rhythms twofold.
The word ‘circadian’ derives from the Latin phrase, circa diem – ‘around a day’. The way this rhythm works is by signalling to the rest of the central nervous system what it needs to do at different points of the day to keep on ticking.
Different bodily cycles, like the sleep-wake cycle or the body temperature cycle, follow distinct circadian rhythms, synchronised with the brain’s master internal clock, which itself is directly affected by the cues from our surroundings, such as light. The absence of light in general, in particular blue light, is how the internal clock knows that it is nighttime and that it’s time for a good dose of melatonin.
So when it comes to nightfall, we are more likely to feel sleepy, because for millennia the human body has been trained to do so. That’s why it’s especially hard to get up during winter when the sun rises much later.
Therefore, if you are exposed to light at this point of your body clock, your body is being deceived into thinking that it’s daytime, and that you can stay up later. If you’ve ever pulled an all-nighter, you might have found that once the sun starts to rise, you don’t feel as tired as you’d expect.
If you’re a shift worker, you may not feel like you have a lot of options here. Blue light blocker glasses can significantly improve the quality of sleep experienced by those working late into the night, as while there’s no cure for being a nocturnal worker, the right glasses will immediately regenerate the presence of melatonin once you have finished work, rather than just having a beer to feel drowsy or — even worse — falling asleep in front of your phone or computer.
Blocking blue light protects your vision
It’s not only your sleep patterns that suffer from the detrimental impact of nighttime overexposure to blue light. Because so many of us spend hours on end on digital devices, the exposure of our retinas to harmful, higher blue light wavelengths has become dangerously frequent.
Blue light is not just a property of artificial light. Computer screens, LED lights, smartphones, tablets — none of these emit anywhere near the amount of blue light as the sun. But by that measure, just as you were never going to go and stare at the sun for hours on end, the proximity of screens, and the amount of time we spend looking at them, can have — literally — unseen consequences.
This is especially true at night. The blue light from our computer screens decreases contrast, which can lead to digital eye strain. Medical professionals assert that this has become very common for both children and adults. As Prevent Blindness explains, nearly all blue light penetrates your eye’s retina, passing right through the cornea and the lens, resulting in Computer Vision Syndrome.
The symptoms of digital induced eye strain may be blurred or double vision, dry eyes, eye redness and itching or fatigue, and depending on how you are sitting, neck and shoulder pain. While these are mostly temporary, they may endure if the use of digital light sources carries on undisturbed.
Limiting smartphone use in the hours preceding bedtime, only using dim lights, and, if you do end up using your phone during the night, investing in blue light screen protectors will see you reap the rewards of enhanced sleep and wakefulness the next day.