What is Blue Light? Everything You Should Know About This Growing Public Health Concern

Home » What is Blue Light? Everything You Should Know About This Growing Public Health Concern
What is Blue Light? Everything You Should Know About This Growing Public Health Concern2018-07-28T10:07:24+00:00




When you think about light, you probably think about sunlight or any other light that your eyes can see. However, light is more than what our eyes can see. It is just a small portion of total amount of light that we are exposed to.


I think that there is not a single person who haven’t heard about UV light, infrared light etc. These are all invisible lights that can have both benefits and negative effects on your health. For example, almost everybody protects itself from sun’s UV lighting with sun creams and glasses but the same UV light is also used like therapy for some skin conditions like psoriasis, vitiligo and others.


In the past most studies were investigating invisible spectrums of light. The most probable reasons for this are the fact that it is invisible and it was noticed that it can have both negative and positive effects on our health. But what about visible light and the spectrums that is is made of? Are they good for our health or not?


Recently, one of the main health concert has become the excessive exposure to blue light and its negative effect on our health. In the past, in electricity-free world, the only exposure to blue light was from the sun during the day time.


However, the amount of blue light that we are exposed to has increased significantly in recent years, mostly due to increasing usage of mobile devices, computers, television, energy efficient lighting etc.


It all started in the 1960s when it was noticed that there is a higher incidence of breast cancer among nurses. After investigating various potential causes, it all came down to the exposure of blue light used in the hospital in the night.


You’re probably asking yourself – Is blue light really that harmful? Are there any positive effects of blue light? How to protect from it?


Today, I’m going to answer to all of these question. I’m going to talk about this blue spectrum of visible light, what is it, what are the benefits and negative effects of it as well as various ways to protect yourself. If you want to find out more about this topic, please read on.


What is blue light?




Before we start talking about the blue light, I think you should also know something about the light in general. Light is a electromagnetic wave made of alternating electric and magnetic fields.


The easiest way to image this waves is to think about ocean waves. Moreover, the propagation of these wave is almost identical to water waves. The only major difference is that you can’t see most of these light waves.


Every light wave has some characteristics – frequency and wavelength. Frequency is the number of waves that passes certain point in one seconds, while the wavelength is the distance between the peak of one wave and the peak of next wave.


Visible lights are electromagnetic waves that our eyes can detect. Our brain interprets certain wavelengths of light as certain colors. On one end of the spectrum there is a red color while on the other is blue color.


Blue light is actually a spectrum of visible light that has wavelength ranging from to  nanometers. They have the shortest wavelengths that our eyes can detect but are high in energy.


Sun is the main and biggest source of blue light but artificial sources are on the rise too




When we think about the light, the first things that come to our mind are the sun and artificial lighting. Although visible sunlight is white, it is actually made of red, orange, yellow, green and blue light rays and many other shades in between them.


It also includes the invisible spectrum of light such as ultraviolet and infrared waves. Together, all these waves create the visible light.


Sun is actually the main source of blue light. When sun’s light rays pass through atmosphere, these short, high energy blue electromagnetic waves collide with air molecules, scattering blue light everywhere. This is actually the reason why the sky is blue when there are no clouds.


Sun was actually the only source of blue light in the past, when when there was no electricity and artificial lighting. However, today we live in a modern world where most places that are populated are illuminated with artificial lighting at night.


Moreover, this modern age of technology caused the existence and ever-growing usage of electronic devices like mobile phones, tablets, computers, laptops, TVs. All these previously mentioned devices are another important source of blue light.


While modern light bulbs are more energy efficient and environmental friendly, they also produce more blue light. All artificial sources of blue light have light emitting diodes or LED that emit blue light. Sun is maybe bigger source of blue light but the proximity of devices and artificial sources to our face and the duration of usage make them an important source of blue light, especially in the night.


Blue light exposure in the day is important for our health




Recently, there are various reports that claim that blue light is bad for our health. Although there is some truth to this fact, blue light is also crucial for our health and proper functioning, especially during the day. This spectrum of light is important for various normal functions such as circadian rhythm, alertness, mood etc.


Every human has a circadian rhythm that lasts around 24 hours. Circadian rhythm is our natural cycle of wake and sleep and it is connected with blue light exposure. During the day, the sun’s blue light raise the level of cortisol, ghrelin and other hormones that keep us awake and hungry.

In ideal situation when there is no light in the night, the secretion of sleep hormone melatonin raises,causing sleepiness and loss of appetite.


So, our body is actually programmed to respond to blue light. During the day, blue light signals our brain that we should be awake, while the absence of sunlight and blue light in the night tells our brain that we should rest.


Blue light is also important for various other functions in our body since most of our organs and functions are connected in some way with circadian rhythm. Blue light also raises awareness, alertness, memory and cognitive functions as well as our mood.


There are also some studies that have found out that blue light is crucial for normal eye and vision development in children and that less exposure to blue light can cause nearsightedness, also known as myopia.


Why recent studies show that excessive blue light exposure is bad for our health?



Blue light is really important and beneficial during the day. However, it can have various negative effects on our health during the night. Blue light is a potent suppressor of melatonin, whether it comes from sun or artificial sources. Exposure to blue light in the night will prevent sleepiness, change our circadian rhythm and may cause various health problems long term.


Blue light exposure in the night will cause our brain not getting proper signal that it is time to rest and sleep, causing negative effect on both quantity and quality of our sleep. There are also various studies that associate blue light exposure in the night with different health issues such as diabetes, obesity, cancer, depression. Eye strain is another problem cause by blue light and visible light in general.


How to reduce blue light exposure




It is actually pretty easy to avoid excessive blue light exposure. First thing you should do is to avoid reading or using colder lights couple of hours before sleep. Use lights that have warmer tones. The more expensive alternative is to buy glasses that have blue light filters built-in.


If you work night shift or use computer during the night, you can also use glasses or buy a screen protector that has a blue light filter. Another great free alternative is to download an app that will change your display’s color and filter blue light. Moreover, you can also use them during day time since they reduce eye strain.


Another simple rule is the ‘’20-20-20’’ rule. Shift your eyes and look at an object that is no less than 20 feet away for 20 seconds every 20 minutes. This rule will reduce eye strain, especially when you spend most of your day at the computer, smartphone or a tablet.


If you’re using e-readers, switch to devices that have the blue light filter in their software. It will switch display’s colors from colder to warmer tones and prevent both melatonin suppression and eye strain. The color shift may feel odd at first but it helps.






Not all of the blue light is bad for your health, especially in the day. However, it can cause a lot of problem if you’re exposed too much in the night. The short term consequences on your sleep are reversible but there are various health problems that it can cause long term that are not that easy to treat..


The biggest problem are the artificial sources of blue light that we use in the night. Unfortunately, they’re not going any time soon so the best way to prevent health problems is to protect yourself. There are various ways to do this and most of them are free.


I hope that with this text you’ve learned more about what is blue light, its positive and negative side and ways to prevent adverse effects that it can have on our health.