How Does the Blue Light Affects Our Sleeping?

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How Does the Blue Light Affects Our Sleeping?2018-07-28T10:03:04+00:00


In the past, the major source of light was the sun and people spent most of their night time in relative darkness. Today, however, with the existence of electricity and artificial lighting, most parts of the world are illuminated at night.


Even though artificial lighting has various benefits, there are many negative effects of light on our health. Moreover, recent studies have shown that it can also contribute to diabetes, obesity, heart diseases, cancer etc.


Not all lights have the same effect on our body. Moreover, the same color spectrum of visible light can have both positive and negative effects. Various studies are examining the positive and negative effects as well as potential usage of different color spectrums of visible light. Great example is the usage of visible light in seasonal affective disorder.


In the last couple of years, one color spectrum of visible light became one of the main health problems and that is the blue light spectrum.


You’ve probably noticed that many electronics manufacturers started including the so called ‘’ Reading mode’’ or ‘’ Blue light filter’’ in their devices that changes the display’s color temperature, providing less eye strain and helping you fall asleep easier, especially in the night before bed time.


Because blue light’s negative effect on sleeping and general health has become one of the major health problems in our society, today I’m going to talk about this spectrum of visible light, its advantages and disadvantages and how it affects our sleeping. If you want to find out more about this, please read on.

What is blue light actually?


When you think about light, the first thing that probably comes to your mind is the sun. Sun is the primary source of visible light. Most people call sunlight the white light but actually it is not. It is made of red, orange, yellow, green and blue light rays as well as many shades in between these colors. Sunlight also includes infrared and ultraviolet rays that are invisible to our eyes.


All these light rays are actually electromagnetic waves that have different energies and wavelengths that determine their color. Together, they create what many people call the white light or visible light.


The visible spectrum is part of the electromagnetic spectrum that is visible to our eyes. Similar to how we sense sound frequency as pitch, we also sense different wavelengths of light as colors. One end of visible spectrum is the red color spectrum with longest wavelength that our eyes can detect. On the other end is the blue spectrum with shortest waves and more energy.

Basically, blue light is one end of the visible light spectrum that consists of waves with lengths ranging from 500 to 380 nanometers.

What are the sources of blue light?


The main source of blue light is the Sun, especially in the past in the electricity-free world. Thanks to its specific wavelength and energy, blue light from the Sun is the one that makes the sky and water blue.


However, we live in a modern age of technology where most of us use devices like smartphones, tablets, notebooks etc. All these devices have displays with light emitting diodes that emit visible lighting, blue light included. Moreover, oher indoor artificial light sources like fluorescent or LED lighting also emit blue light.


These electronic devices emit just a small amount of blue light in comparison to Sun. However, the amount of time people spend using these devices and the proximity of these devices to our faces raises the exposure level.

Are there any benefits of blue light?


Not all blue light is bad for our health. Actually, there are many normal functions of our body that are dependant of blue light. One of the most important is the blue light’s role in control of circadian rhythm.


Every human has a circadian rhythm, the human body’s natural cycle of wake and sleep. Circadian rhythm lasts around 24 hours, on average 24 and a quarter hours. Not everybody has the same circadian rhythm. People who stay up late have circadian rhythm that is more than 24 hours, while people who wake up early have rhythm shorter than 24 hours.


During daytime, exposure to sun’s blue light stimulates the production of hormones such as cortisol and melatonin which keep as awake and hungry. Moreover, it also boosts awareness, helps cognitive and memory function and elevates our mood.


In the night, the secretion of these hormones lowers, while the secretion of melatonin raises. Melatonin will cause sleepiness at night time along with temperature drop and less hunger.


Some recent studies have also shown that insufficient exposure to blue light in children can affect the development of eyes and vision. Moreover, it can also contribute to myopia or nearsightedness.


How does the blue light affects our sleeping?


As I’ve previously mentioned, our bodies are programmed to respond to blue light. During the day, the blue light signals our body that we should be awake. On the other hand, the absence of sun’s blue light during night time informs our brain and body that we should rest.


The problem in today’s world is the usage of artificial sources of blue light, especially during night time and before sleep. They lower the normal secretion of melatonin and prevent you from falling asleep. Some researchers confirmed that blue light is potent suppressor of melatonin.


Excessive exposure to blue light in the night will change the sleeping pattern and body’s natural circadian rhythm. It will also have negative impact on overall health and alertness. Moreover, because circadian rhythm is one of the if not the most important body’s natural clock, it can also shift other clocks that control function of body’s organs.


Various studies has shown consequences of excessive blue light exposure during night time. One study confirmed that excessive blue light exposure causes short-term sleep disruption, while other has shown that after just 5 days the melatonin levels drop over 50% causing longer time to fall asleep, less REM sleep (the restorative phase of sleep when we dream) and grogginess the next day in those who are reading e-book before sleep.


How to avoid blue light’s side effects on our sleeping cycle?


There are several ways to avoid excessive blue light exposure in the night time.


Since use of mobile devices before sleep is one of the most common reasons of excess blue light exposure, it is advised to avoid looking at display one to two hours before sleep. If you can’t avoid looking at screen entirely, try cutting back on the blue light as much as possible.


People who like to read before sleep should avoid e-readers at night and use standard books with orange or red reading lamp. If you don’t want to spend money, candles and candlelights are good alternative too.


Use warmer indoor lighting instead of colder lighting in your house. There are yellow tinted LED light bulbs available on the marker.


If you spend most of your work time at the office sitting at the desk, in front of the computer, you should consider getting orange tinted glasses that will filter out blue light. Another great option is a screen protector that has the same filter as orange tinted glasses.


Because we live in a technology era where we spend majority of our time looking at our smartphones, tablets and computers, you can download app that will filter blue light and reduce blue light exposure. This software will shift your display to warmer, more red tones. It might be different and awkward when you use this app for the first time, but you will notice less eye strain and wakefulness during night time.


Today, most manufacturers have this blue light filter option built into their software so you don’t have to download it. If not, there are various free apps available at the app store. Moreover, there are also applications for desktop computers and laptops like F.lux that you can download for free. This application even does automatic screen adjustments  based on your timezone and time of day.



Blue spectrum of visible light may be beneficial in the day, allowing us to be awake, be more reactive, alerting and productive but it also gives us a rough time falling asleep at night. Thankfully there are various simple yet effective ways to prevent these adverse effects at night.


However, don’t forget to expose yourself to enough bright light during the day. Many researchers say that even 15 minutes of being outdoors during the day is enough for positive effects on your productivity, alertness, mood, memory and cognitive functions etc.


I hope that with this text you’ve learned more about blue light and its adverse effect on our sleeping and general health and ways to avoid it so next time before being exposed to excessive amount of blue light during the night you know what you to do.