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How Does Blue Light Affect Sleep Quality?

I'm Sam. I enjoy writing about sleep and mental health-related topics as well as ways to prevent stress and relax.


Why Can't I Fall Asleep?

There are many factors that affect how easy it is to fall asleep and the quality of your sleep. One of these factors is light, especially how blue light affects sleep. Your body’s natural sleep schedule is tied to something called the circadian rhythm. The circadian rhythm is an internal clock that impacts your body’s mood and hormones, preparing it to either be awake or asleep.

Light and Circadian Rhythm

The most important factor in setting your body’s circadian rhythm is light. Exposure to natural sunlight in the day signals to your body that it should be awake, while darkness at night helps signal that you should be asleep. Getting exposure to natural light in a consistent pattern can help your body settle into a regular sleeping pattern.

Electronic Devices Artificial Lighting

Unfortunately, the prevalence of artificial light and electronic devices means that we’re often exposed to light outside of the natural cycle, which can throw off our circadian rhythm and our sleep-wake cycle. One of the worst perpetrators of disrupting our circadian rhythm is blue light. Most sources of light contain lights of different wavelengths.

Blue Light and Sunlight

Blue light is particularly prevalent in sunlight. This makes blue light great during the day. It helps us to feel awake and alert. Some people even intentionally use artificial blue light during the day to increase alertness and boost their mood.

Blue Light at Night

At night, however, blue light is a whole different story. The sun isn’t the only thing that emits blue light; electronic devices such as phones, computers, and tablets do too. This means that even after the sun has set, many of us are getting lots of exposure to artificial blue light.

Blue Light and Melatonin

Blue light has been shown to slow the release of melatonin in the brain. Melatonin is a hormone that helps reduce alertness, and it’s essential for good sleep. This is why exposure to blue light close to bedtime can aggravate sleep disorders, make it hard to fall asleep, and decrease the quality of sleep.


Reduce Your Exposure to Artificial Light

Now that we know how blue light affects sleep quality, we can take some steps to improve our lives. The best way to solve this problem is to reduce your exposure to blue light for one to two hours before going to bed. Do your best to limit your exposure to electronics, including the TV, computer, and phone. When you go to bed, make sure that your phone screen is turned off so it doesn’t let off blue light while you’re trying to sleep. If you need to use your computer close to bedtime, there are a number of programs (such as f.lux) that will adjust the color of your computer screen in the evening.

In addition to turning off electronics, you may also want to dim artificial lights around your home close to bedtime. If you’re serious about reducing your exposure to blue light, you can purchase a pair of blue-light-blocking glasses. These yellow-colored glasses help to filter out blue light before it reaches your eyes. These simple steps can help you get significantly better sleep.

Light and the Circadian Rhythms

You've seen that light and sleep are closely connected. Both of these are connected to a natural rhythm within the body, called the circadian rhythms. Circadian rhythms affect a number of things within our bodies, including our temperature, our mood, and the release of hormones. Perhaps most importantly, our circadian rhythms affect our sleep-wake cycle.

The circadian rhythms follow a 24-hour cycle that primarily responds to light and dark. Circadian rhythms help your body to be ready for activity during daylight. At night, circadian rhythms contribute to producing melatonin and producing sleep. Because of these rhythms, light and darkness are very important to make your body naturally ready to fall asleep.

Blue Light From Phones and Tablets

In earlier centuries, humans followed a pattern of life that depended on daylight. When it was light outside, people were awake and outdoors. When it was dark out, they were likely asleep. With the advent of new technology such as electric lighting and more options for entertainment, modern humans are often awake far into the night and may sleep significantly into the daylight.

We’re also often near artificial lights, whether they’re from light bulbs, TVs, computers, or phones, frequently at night and close to when we’re going to sleep. If you want to reduce the impact of blue light on sleep you should leave phones and tablets out of the bedroom when possible. At least stop using your phone thirty minutes to one hour before you go to sleep. Cutting blue light exposure earlier is better of course.

All of these factors can throw off our natural circadian rhythms. This can inhibit the natural wake-sleep cycle that makes it easy for you to fall asleep, gives you a solid night’s rest, and then helps you to wake up feeling energized. It’s a modern problem that can aggravate insomnia for many people. One way to reduce this problem is through light therapy.

What Is Light Therapy for Sleep?

Light therapy uses artificial light to adjust your circadian rhythm and help you sleep. In order to try light therapy, you’ll need to purchase a light therapy box. These boxes produce a bright light that mimics sunlight. You turn this light on and expose yourself to it at carefully timed parts of the day in order to adapt your body’s sleeping pattern. If, for example, you spend most of the day indoors and don’t get much exposure to natural light, you may want to use light therapy during the day to reinforce a natural circadian rhythm.

If you wake up early in the morning before it’s light outside, you can use a lightbox in the morning to signal to your body that it’s time to wake up. Some lightboxes will even light up gradually before your scheduled wake-up time to simulate the effect of the sun rising.

The key to effective light therapy for sleep disorders is consistency. You need to use it at the same time every day over a period of time. This helps to create a consistent and regular sleeping pattern. These effects will be more definite if you’re also making an effort to go to bed and wake up at the same time every day. You need to consistently enforce a standard sleeping schedule if you want your body to settle into a natural rhythm.

If you commit to using light therapy as part of a consistent sleeping schedule, it can help you to fall asleep more easily at night and feel more energetic during the day.

In order to make light therapy as effective as possible, you may want to speak to your doctor or to a sleep therapist to determine the right timing for using light therapy. They can also help you to choose a lightbox that has the right level of intensity. Light therapy may not be effective for everyone, but it may help to treat your insomnia and improve your body’s natural sleep-wake cycle.

Start With Simple Sleep Hygiene

I would advise talking to a doctor before buying any expensive equipment. The same goes for blue light protection glasses or adding these filters to your normal glasses. If you have trouble sleeping first try to improve your overall sleep hygiene. Reduce blue light in your environment before going to bed. Cut back on using electronic devices before sleep, make sure your room has a nice temperature and is dark enough.


This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2019 Sam Shepards


Laynie H from Bend, Oregon on July 19, 2019:

I definitely use blue light filter lenses and an app on my computer. I've always been paranoid of the sleep cycle and hormone interference. Hopefully soon, our data will catch up. Very interested to learn more. Thanks for sharing this!

Sam Shepards (author) from Europe on July 19, 2019:


Thank you, I didn't really delve into the effect of blue light on eyesight. In normal quantities, it is no problem, but there are indeed signs of negative impact with prolonged exposure. Especially no kids start using tablets and phones at a very young age this could pose a serious issue. We also see more and more filters coming out and manufacturers opting for a reduction in blue light from their devices.

Liz Westwood from UK on July 19, 2019:

You have tackled an interesting topic. I am reading a lot about this at the moment. I have also come across some comments about the detrimental effect on our eyesight of exposure to blue light.

Lorna Lamon on July 19, 2019:

The health benefits of maintaining a good sleep routine are numerous, therefore the importance of not using devices at least two hours before sleeping cannot be underestimated. Thank you for sharing.

Laynie H from Bend, Oregon on July 18, 2019:

You touch on some really important points here. Blue light is a real issue—we are only now starting to realize some off the side effects.