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Blue Light and Sleep: Understanding the Connection

Craig Primack, MD, FACP, FAAP, FOMA

Reviewed by Craig Primack, MD, FACP, FAAP, FOMA

Written by Hadley Mendelsohn

Published 10/18/2024

If you’re reading this, chances are you’re using a screen right now, which means you’re likely getting some exposure to artificial blue light. Artificial blue light — a type of light emitted by screens and other modern tech — has been a popular topic as of late, so you may have come across some concerning information about blue light effects on sleep and eyes.

But don’t worry — with the right info and strategies, you can manage its impact. If you’re curious about how blue light affects health, particularly our sleep patterns, you’re in the right place.

Ahead, we’ll go over how artificial blue light can have negative effects on sleep quality and explain why getting enough high-quality sleep is an essential component of both physical and mental health. We’ll also share plenty of tips to help you manage your exposure to blue light.

Let’s dig in.

Our eyes rely on light from the environment to help us process our surroundings visually — essentially, to see. Simply put, when light enters our eyes, it carries energy, which nerve cells convert into signals. These signals are then sent to our brains, allowing us to interpret what we see.

Blue light is a specific type of light within the visible spectrum (light that humans can see) and consists of various wavelengths. Blue light has short wavelengths and higher frequencies than other colors, like red light. Those short blue wavelengths have a higher frequency, which means they carry more energy.

Some forms of blue light are natural, like sunlight. Before advances in technology, humans primarily relied on natural light sources, including the sun, moon, and stars.

While all light plays an important role in our sleep-wake cycle by regulating mood, hormones, and attention, blue light is especially significant because it helps us feel more alert during the day.

Sources of Blue Light

Thanks to modern technology, we’re now exposed to more artificial blue light than ever before — especially at night — through various devices and energy-efficient light sources.

Most of us know that blue light from phones is a prominent source. Other blue light sources include:

  • Tablets

  • Television

  • Fluorescent lights

  • E-readers

  • LED lights

  • Computer monitors

Since there’s been concern over the effects of these devices’ blue light on health — particularly sleep patterns — we’ll explore the relationship between light and the sleep-wake cycle.

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Your sleep-wake cycle, or circadian rhythm, is basically your body’s internal clock. But what do we mean by "internal clock"?

This clock tells you when to wake up, when to eat, and when to go to bed, among other activities. How does it know when to do all this? Your body relies on environmental cues to train it to crave the things it needs at certain times of the day. Light is one of these environmental cues. It’s one of the reasons we tend to wake up with the sun and wind down when it sets.

Hormones also play a vital role in this process, helping to keep your internal clock running smoothly so your body knows what it needs at different times. One important hormone affected by light is melatonin.

Here’s how melatonin works within the context of your circadian rhythm:

  • Melatonin is produced in a small gland in your brain called the pineal gland. At night — or in the absence of sunlight and blue light — stored-up melatonin is released to help slow down brain activity. Your body can also convert serotonin into more melatonin. Serotonin is another chemical naturally found in the brain, and it’s sometimes referred to as the “feel-good chemical.”

  • Melatonin signals to your body and brain that it’s time to rest, so higher melatonin levels increase sleepiness.

  • Sunlight and artificial blue light can help prevent your body from turning serotonin into melatonin. Some research suggests that blue light exposure during the day can enhance cognitive performance, alertness, and reaction time — helpful for quick decision-making and coordination.

So it’s a bit of a delicate dance, and whether light is good or bad really depends on the time of day and the type of exposure you’re getting.

Now that we’ve explored how light affects your wakefulness and sleepiness, you might be wondering: Does blue light keep you awake? Can it lead to melatonin suppression? The short answer is yes, it might.

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Since one of the natural functions of blue light is to help us feel more alert by suppressing melatonin production, it’s possible for it to interfere with our sleep-wake cycle when we’re exposed to it too much at night.

Some research suggests that it can even lead to insomnia, reduced sleep duration, and increased sleep latency (the time it takes to fall asleep).

Since it’s an emerging field of study, the research on the pros and cons of blue light is somewhat mixed. Plus, some studies say that bright light — regardless of the wavelength color — may also interrupt the circadian rhythm.

One thing we know for sure? Getting between seven and nine hours a night is vital for overall health and well-being. If you’re not getting enough restful sleep — including enough REM and deep sleep — you may be at risk for chronic sleep deprivation.

Some of the health consequences of chronic sleep deprivation include:

  • Daytime sleepiness. This is often the most noticeable sign of not getting enough rest. If you feel groggy during the day, it might indicate that your body hasn’t fully recharged. This can make it tough to focus on tasks and keep up with your responsibilities.

  • Impaired function. Research shows that people who consistently sleep fewer than six hours a night are at a greater risk of accidents. Translation: Sleep is crucial for our alertness and decision-making.

  • Weakened immune system. Lack of sleep can take a toll on your immune health. Studies indicate that individuals who sleep less than seven hours are nearly three times more likely to catch a cold than those who prioritize their sleep.

  • Increased risk of mental health issues. Sleep and mental health are deeply connected. If you’re feeling anxious or depressed, it can make falling asleep more difficult. Unfortunately, poor sleep can also worsen those feelings, creating a challenging cycle.

  • Higher risk of heart disease. Chronic sleep deprivation is linked to an increased risk of heart-related conditions, including heart disease and hypertension (also known as high blood pressure).

  • Potential for weight gain. Research has found connections between sleep problems and a higher body mass index (BMI). For instance, one study found that women who sleep well through the night tend to have less body fat and more lean mass.

If you’re experiencing any of these issues, it might be a sign to take a closer look at your sleep habits.

Other Effects of Blue Light

On top of its potential to impact our sleep quality, artificial blue light might also be linked with daytime problems. Specifically, our eyes aren’t naturally equipped to block out excessive artificial blue light.

So, during the day, this can create eye strain, especially if you have a job that requires you to be on your devices all day. Digital eye strain can lead to:

  • Eye fatigue

  • Blurred vision

  • Irritated or burning eyes

  • Dry eyes

  • Headache

  • General discomfort

Now that we’ve talked about the potential risks of blue light, you might be wondering how to manage it in a tech-heavy world like ours.

While avoiding screens entirely isn’t realistic for most of us, there are some practical strategies you can use to protect your sleep and overall well-being:

  • Avoid late-night screen time. If possible, try to unplug from your electronic devices — like smartphones, televisions, and computer screens — at least three hours before bedtime. This could give your body a chance to wind down without the stimulating effects of blue light.

  • Get blue light-blocking glasses. Yep, these exist! Some special glasses can help filter out blue light, making it easier on your eyes, especially if you need to use screens in the evening.

  • Install blue light filters. Many devices now come with built-in blue light filters or “night mode” settings. You can also download apps that adjust the screen's color temperature, reducing the amount of bright light emitted.

  • Use a warmer nightlight. Consider using a red light or warmer-toned bulb as a nightlight. If you’re not ready to change out your bulbs, a simple dimmer switch can help create a cozy, softer glow.

Sometimes, blue light exposure is unavoidable. If you can’t always limit your exposure to blue light before bed, you can also try to improve your sleep habits by doing things like:

  • Exercising during the day and eating foods that support overall health, including energy levels and sleep.

  • Cutting out late afternoon caffeine so you aren’t too energized when it’s time for bed.

  • Using an alarm clock that wakes you up slowly so you don’t wake up as abruptly, which can be jarring.

  • Installing blackout shades that block out exterior light or anything that might disturb your sleep cycle.

  • Making sure your pillow, mattress, and bedding are supportive and comfortable.

If you still have sleep problems after adjusting your routine, it may be time to see a healthcare provider. They’ll help you come up with a treatment plan, possibly involving sleep medicine, or figure out if a sleep disorder like sleep apnea is causing your issues.

In the meantime, check out our sleep hygiene guide for more in-depth sleep tips.

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Blue light is an integral part of our modern lives, especially with the screens we use every day. While it can help us feel alert and focused during the day, excessive exposure at night can interfere with our sleep quality. Here are some key takeaways to keep in mind:

  • Blue light is a part of the visible light spectrum, present in both natural sunlight and artificial sources like screens and LED lights.

  • Why does blue light keep you awake? It suppresses melatonin production, which makes it harder for our bodies to wind down at night. This might lead to sleep issues such as insomnia, reduced sleep quality, and, thus, daytime fatigue.

  • Chronic sleep deprivation can affect your health in many ways, including increased risks of accidents, weakened immunity, mental health challenges, and heart disease. Needless to say, proper sleep hygiene is crucial.

  • You can take simple steps to protect yourself from excessive blue light. These include things like limiting evening use of screens, using blue light-blocking glasses or filters, and choosing warmer light sources at night.

Long story short? Blue light isn’t inherently bad. But the effects of blue light on sleep and our bodies can be negative and may mess with sleep patterns, so it’s important to be mindful of when and how much artificial blue light you’re exposed to.

Remember, quality sleep is a vital part of living a healthy life, and you deserve to rest well.

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This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

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