The Effect of Blue Light on Sleep

While you may think of sleep as something that occurs naturally, there is actually a lot that goes into this process. Namely, the way that your body reacts to external stimuli can impact whether or not you will have a good night’s sleep. Since technology is such a big part of our lives these days, it stands to reason that we take a closer look at the effect it can have on our sleep. In this article, we focus on blue light and how it may influence sleeping patterns.

What Is Blue Light?

light affects sleeping

To understand what blue light is, you have to sit through a short science lesson first.

So here’s the deal:

Blue light is actually everywhere – it is a part of the sunlight that you see. Now sunlight is made up of both visible light and invisible radiation. Without going into too much detail, blue light falls under the visible portion of this spectrum. In fact, about one-third of the light that you can see can be considered blue light.

The other thing that you need to recognize about blue light is its wavelength. It has a shorter length which basically means that it has a greater amount of energy. The blue light that is given out by your digital devices is a man-made source of what the sun typically produces.

What Devices Emit Blue Light?

woman on phone

The short answer to this question would be: everything. If you are using an electronic device that has a digital display then it is giving off blue light. This includes cell phones, television screens, computers (and laptops), and tablets. If your mp3 or mp4 player has a display screen, it probably produces blue light as well.

Many of the devices that you use today relies on LED back-light components to make your screen brighter and clearer to view. These LED lights are made up of rather powerful blue light. So, depending on how much you use this variety of digital devices, you are actually exposing yourself to a considerable level of blue light.

How Does Blue Light Affect Sleep?

Now, that you are aware of what blue light is and where it comes from, it is time to move onto the most important thing – how does it impact your sleep. Well, believe it or not, it affects various aspects of your slumber, preventing you from getting the shuteye that you need. This section deals with how and why blue light keeps you awake.

How Does Blue Light Affect the Circadian Rhythm?

You can think of the circadian rhythm as an internal clock. In essence, it tells your brain whether it is time to feel sleepy or alert. There are a few factors that govern your circadian rhythm but one of these is light. During the daytime, when your eyes are exposed to light, your brain is signaled that you need to stay awake and be aware. When it becomes darker, your brain is given the opposite signal.

If you are wondering how blue light plays into all of this, it is simple. Remember when we covered that much of the light that we actually see during the day is blue light? Well, this is basically being represented by your mobile phones and laptops. So, if you are using technology before bed, you are really telling your brain that it is daytime and that you need to stay awake.

How Does Blue Light Affect Melatonin Levels?

Once again, there is a little bit of science involved in this part to really understand the relationship between melatonin, sleep, and blue light.


First things first, you need to know about the SCN, which is a part in your hypothalamus. It is stimulated by light and, in turn, sets off a bunch of other reactions in your body, including sleep.

One of the things that the SCN is responsible for is to stimulate the pineal gland which produces melatonin. This hormone is fundamentally what lets your body know that it is time to go to sleep. It will not make you fall asleep but it does make you feel more relaxed.

As you can imagine, the SCN also plays a role in wakefulness. When the SCN is alerted to the presence of light, it triggers certain actions in your body. Namely, it increases your body temperature and works to release certain hormones such as cortisol. These events are what cause you to wake up.

Blue light acts like daylight, even if you are in an otherwise dark room. It stimulates the part of your brain that tells the rest of your body that you should stay up and be alert.

This, in turn, makes it difficult for you to fall asleep.

How Does Blue Light Affect the Sleep Cycle?

The human sleep cycle is essentially made up of four stages. These stages can be divided into two categories – Rapid Eye Movement (REM) sleep and Non-REM sleep.

So here’s how it works:

Non-REM sleep consists of three of the stages of sleep known as N1, N2, and N3. The first stage that you experience as you doze off is N1. You then to move onto N2 which is the stage that you will spend the most amount of time in, and then move onto N3.

After about an hour and a half after you have been asleep, you will enter the REM stage. In the first cycle, you will not spend all that much time in this stage. However, as your sleep progresses, this period will get longer.

There are a couple of ways that blue light can affect your sleep cycle. First, if you are exposed to blue light before your bedtime, then your brain is still wide awake. This means that it will take you a longer time to transition from a wakeful stage to the N1 stage. It can also cause the redistribution of the amount of time spent in each cycle. This means that you can wake up feeling groggy or unrested, even if you have seemingly had a full night’s sleep.

How to Prevent the Effects of Blue Light on Sleep

So, we have established that blue light can have a negative impact on your sleep. The more blue light that you are exposed to right before your bedtime, the less likely you will get your required amount of sleep. This begs the question, what can you do about this?

Especially for children, it is a good idea to establish a bedtime routine that is free of electronics or devices. This helps your brain to transition to ‘sleep mode’ and can make it easier for you to fall asleep.

Now, perhaps because of your job, this isn’t always possible to do. Or, maybe because you need to stay on call, you have to sleep with your cell phone. Either way, a blue light filter can help to alleviate the negative effects of the light emitted by electronic devices. These filters can come in various forms but they perform the same function – they limit the amount of blue light that actually reaches your eyes.

Blue Light Filter Apps

There is a good chance that you are using your smartphone or tablet right before bedtime. In this case, your best option would be to download an app that allows you to change the light settings on your phone and tablet. Now, there are quite a few available but we have narrowed down what works best:

  • Twilight: if you have an Android phone or tablet, this is the app that will be most useful for you. It limits the exposure to blue light after sunset and provides your screen with a red filter to offset the blue. Also, it allows you to reduce the backlight even further than what the settings on your phone permit.

Twilight Sleeping App


  • Night Shift: if you own an Apple products, then this is the feature for you. It is already set up on devices that have a system greater than iOS 9.3 running. It makes the display look warmer so that your brain is reminded of sunset, decreasing your levels of wakefulness.

apple blue light reduction

  • Night Light: for those that have a device that has Microsoft 10, you too have a built-in This, too, gives off warmer colors so that the impact of the blue light is greatly reduced.

Night Light option

Blue Light Filter Accessories

If you are looking for something with greater impact, you may want to try external accessories for both you and your devices. These are supposedly more effective at reducing the amount of blue light that you are exposed to.

For a more constant fix, you can turn to glasses or eyewear that have blue light filters. These come in the form of either anti-reflective coatings or photochromic lenses. The anti-reflective coatings simply block the blue light whether you are indoors or outdoors. While the photochromic lenses do the same, you will find that the transition from indoors to outdoors or vice versa is a lot smoother. These lenses also darken when they are exposed to sunlight.

There are also physical shields that you can place on the screens of your smartphones, computers, and tablets. Unlike the shields of old, these are basically thin coverings that can be fitted over the screen. This minimizes much of the blue light that is emitted. Some of these coverings can even protect your screen. It is important to remember that when purchasing such screens that you focus on ones that filter light between 420 – 480nm for best results.

How Long Before Bed Should You Turn Off Electronics?

So, it is safe to say that using electronics before bedtime is a big no-no. Of course, considering that we live in a world that is dominated by smartphones and other devices, it can be difficult to use them less just so you can get a better night’s sleep.

To start with, you should stop using all devices up to an hour before you are supposed to go to sleep. This way, your brain has enough of time to gradually move from wakefulness to a more relaxed, calm state where it is easier to achieve sleep. You will find that you fall asleep faster once you adopt this tactic.

There is more that you can do, however. For instance, about two hours before you go to sleep, you can limit how much time you spend staring at screens. This, too, will help you to transition to a sleeping state more quickly.

Other Effects of Technology on Sleep

emotional stress

We have taken a look at all of the ways that technology and the blue light that accompanies it can make it difficult for you to fall asleep. This, however, is not all that there is to it. For instance, simply having a mobile device close to where you sleep can cause disruptions in your slumber. The pings and alerts from emails, messages, and various other notifications can jolt you from your sleep. Not to mention your phone lighting up every time you get a notification can cause you to be even more alert.

Technology can also lead to emotional stress that can make it difficult for people to nod off. Smartphones are typically associated with being able to stay connected with the rest of the world. So, powering down for the night or turning your phone off, can instigate a “fear of missing out” in many people. This anxiety can not only make you toss and turn at bedtime, it can also mean that your sleep is fitful.

Alternatives to Using Technology at Bedtime

Sleep while reading book

One of the reasons that you might find yourself running back to your phone or tablet after fifteen minutes of disuse is boredom. With nothing to do before bedtime, you will be eager for some form of entertainment. Well, luckily for you, there are a few things that you can do.

For instance, you can create a proper bedtime atmosphere for yourself. This includes dimming the lights and making the room that you are sleeping in cooler. A few hours before bed, you can also take a warm shower to help you sleep.

Now, to stave off boredom, there are a few things that you can do as well. At the top of the list would be to read a book, preferably a paperback one. You should avoid anything too stimulating such as a thriller or mystery. This will simply cause your brain to kick into high gear. Instead, read something that is slightly comedic or perhaps a non-fiction book.

The other thing that you can do is listen to music. The key here, though, is to listen to tunes that you are familiar with, perhaps some of your favorite songs. Again, it works best if these aren’t too energizing. Instead, they should just be pleasant to listen to.

There are plenty of other hobbies that you can take up before you go to sleep. This includes knitting, journaling, or even coloring. Spending some time with your pet can also help to decrease stress levels and leave you feeling calm enough to go to sleep.

This is all that you need to know about blue light and the impact that it can have on your sleep. You are now more than able to solve your sleeping problems related to technology.

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