As laptops, tablets and smartphones have become more and more integrated into our daily lives, it makes sense to be aware of any potential negative effects they might have on our health. You’ve likely heard the term ‘blue light’ being bandied about, with suggestions it contributes to all kinds of nasties; from headaches and eye strain to straight-up insomnia. But - we hear you ask - what exactly is blue light, and how is it connected to our use of digital devices? Say no more, as we’ve got the lowdown…
To understand blue light and its various effects, we need to take a look at the bigger picture, also known as the ‘electromagnetic spectrum’. When you step outside into sunshine (rare enough in Ireland, we know), you’re actually basking in a whole host of electromagnetic particles, all of which travel in waves. Some of these waves are visible to the human eye, others - like the ultra-violet or UV rays that tan or burn our skin - aren’t. These waves also vary in terms of their length and strength, as well as how much energy they emit, with shorter wavelengths emitting higher energy. The electromagnetic spectrum is made up of red, orange, yellow, green and blue light, with blue being both visible to the human eye and emitting a high amount of energy. Therefore it’s known as HEV (high-energy visible) light.
Still with us? Here’s some more sciencey stuff: wavelengths are measured in nanometres (that’s a mind-blowing one-billionth of a metre, fact fans), and blue light ranges from about 380 to 500nm, compared to red light’s 700nm. Put simply, it’s one of the shortest, highest-energy wavelengths on the spectrum, and accounts for an impressive one-third of all visible light. But before you start fashioning a homemade tinfoil hat to banish all blue light forever, it’s important to bear in mind why it’s useful in the right context…
Sunlight is the strongest producer of blue light, and in that setting, it’s beneficial for our bodies. During the day, those natural blue wavelengths help boost attention levels, making us more alert and productive. It also contributes to our mood; heard of Seasonal Affective Disorder, or SAD? Caused by a lack of sunlight during autumn and winter months, this condition can lead to depression in extreme cases. The lamps used to treat it contain a high amount of HEV blue light, helping to mimic sunshine and in turn, banish those winter blues. Sunlight exposure also keeps our circadian rhythm (the natural 24-hour cycle we adhere to) in check, so the body knows to wind down and fall asleep as night approaches. So hey, it’s not all bad! However…
The potential negative effects of blue light have come to the fore in recent years because it’s also emitted by digital devices; think smartphones, computers, TVs and tablets. Given that most of us spend at least eight hours a day in front of a screen at work, get our news from digital platforms, share updates and pictures on social channels, and communicate with friends via messaging apps, you start to understand how much artificial blue light we’re exposing ourselves to. What’s more, while the human eye does a great job of blocking out UV rays, it’s not very good when it comes to blue light - in fact, pretty much all of it reaches the light-sensitive retina at the back of the eyeball. Factor in the irresistible urge to scroll to the depths of our Facebook feed under the duvet at night, and it makes sense that the body’s natural rhythm could become disrupted over time.