what does blue light do to your brain

What Does Blue Light Do To Your Brain?

Last modified on May 23rd, 2023

You may have heard of blue light glasses, which have become increasingly popular as we’re all so attached to our devices, but you could wonder, what does blue light do to your brain exactly? Blue light can affect your sleep and mental health.

Before the creation of artificial lighting, the sun was the primary light source. People spent the night hours in darkness. Now, we’re constantly exposed to artificial light. The lights we use and are exposed to at night can affect our biological clock and circadian rhythm. These lights interfere with sleep, and some research indicates artificial light may contribute to chronic diseases like obesity, heart disease, cancer, and diabetes.

What Is Blue Light?

Blue light is high-energy visible light or HEV light. It’s a color in the visible light spectrum. The human eye can see it. Blue light is a short wavelength, producing higher energy than longer wavelengths.

The eye can’t filter blue light effectively, unlike other types of light. More passes to the retina through the eye.

Sources of blue light include:

  • Computer monitors
  • Laptop screens
  • Smartphones
  • Tablets
  • TVs
  • CFL and fluorescent bulbs

The digital devices we use are especially concerning in terms of blue light because we hold the screens close, we use them so long, and there’s a cumulative effect that occurs over time.

For the past two decades, screen time has been on the rise. We’re exposed to screens for more than 13 hours daily. An estimated 65% of Americans express symptoms of digital eye strain. Symptoms of eye strain from digital devices can include blurred vision, headaches, eye strain, and dry, irritated eyes.

Blue wavelengths can have benefits when we’re exposed during the day. They can improve mood, attention, and reaction time. At night, it’s when blue wavelengths become disruptive.

What Does Blue Light Do To Your Brain and Mental Health?

Blue light can affect mood, sleep, and emotions. For example, blue light exposure close to bed can affect circadian rhythms, which control the sleep-wake cycle. Blue light at night can affect hormone secretion, nerve signaling, and the brain’s ability to adapt to changing situations. Excessive blue light can contribute to sleep disorders and mood disorders like depression.

Light is one of the most powerful environmental factors affecting our brains. Blue light creates the most significant brain response of all colors in the spectrum.

Light or its absence plays a role in maintaining your circadian rhythm. Circadian rhythm affects how your brain regulates behaviors and biological processes.

Our brain will produce different hormones to keep us feeling energetic during the day and then sleeping at night. Our circadian rhythm is our internal clock. Light is an environmental cue that signals our brain to release the right type of hormones at the right time of day, depending on the needs of our bodies.

In the morning, blue light signals the brain to lower melatonin levels. Melatonin is a hormone that regulates circadian rhythm and energy metabolism. The drop in melatonin then signals serotonin to raise energy levels. At night, as the light fades, it’s supposed to cue our body to raise melatonin levels, helping us sleep.

When exposed to artificial blue light in the evening, it can affect the balance of many hormones, including not only melatonin but also dopamine and serotonin. Dopamine and serotonin affect emotions and mood, which can contribute to mood disorders when they’re dysregulated.

In research with models using flies, exposure to 12 hours of blue light per day impaired aging phenotypes. It affected retinal cells, causing damage and leading to faster brain neurodegeneration. According to this fly study, blue light exposure leads to the expression of stress-responsive genes in old flies but not in young ones. Researchers theorized that cumulative blue light exposure is a stressor during aging.

Light and Mood

There are direct and indirect links between mood and light. When one of three photoreceptors responds directly to light, the projections reach brain regions that affect our emotions. Think about how you might feel more cheerful on a sunny day. However, that indirect connection to systems can lead to mood disorders when disrupted.

The systems indirectly connected to light and mood disorders include:

Studies have indicated structural changes in the brains of people who have severe disruptions to their circadian rhythms, such as international flight attendants.

Circadian Rhythm

Circadian rhythm is our mental, physical and behavioral changes following a daily cycle. These respond to light and darkness in our environment.

In humans, our circadian rhythm synchronizes behavioral and biological processes, which are partially regulated by sunlight. The circadian rhythm regulates:

  • Sleep-wake behavior
  • Gene expression
  • Cellular function
  • Hormone secretion

Because of the importance of these systems, evidence is increasingly showing their disruption can lead to mood disorders, metabolic dysfunction, and some types of cancers.


Blue light exposure at night blocks melatonin production, and sleep disturbance is a major factor that contributes to the onset of mood disorders and their ongoing symptoms. Sleep disruption is also one of the primary symptoms of major depression, bipolar disorder, post-traumatic stress disorder, and generalized anxiety.

When your sleep is disturbed, your body can’t complete its full circadian cycle, leading to mood disorders.

How To Reduce Blue Light Exposure

If learning the answer to “what does blue light do to your brain” makes you concerned, there are things you can do to limit your exposure.

Tips to reduce blue light exposure include:

  • Wear blue light glasses: These glasses are inexpensive and widely available on Amazon and help reduce the effects of blue light on your brain and sleep patterns. Blue light glasses block the blue light wavelength from reaching your eyes.
  • Limit your screen time: Try to avoid screens for several hours before bed. If you’re getting longer intervals of light exposure, it can disrupt your brain, sleep, and mood. Turn off digital screens two hours before you head to bed. You’ll likely sleep better and feel better.
  • Go outside: Get morning light exposure when you wake up. When you get outside during the day, it resets your circadian rhythm and signals to your body what time it is.
  • Adjust screen brightness: If you want to look at screens in the evening for any reason, you can adjust your screen’s brightness and turn it down in the evenings.
  • Change your bulbs: Some people like to use red light bulbs in their house in the evening, which can mimic a sunset. Even if you don’t want to do this, if you want to change your bulbs to a warmer hue, it can reduce your exposure. LED bulbs tend to have higher amounts of blue light.

Final Thoughts—What Does Blue Light Do To Your Brain?

What does blue light do to your brain?

Blue light exposure during the day can have benefits, including increasing energy and cognitive function. However, extended blue light exposure, especially in the evenings, can have detrimental exposure.

Evening and excessive blue light exposure can raise your risk of insomnia, sleep disorders, and mood disorders and contribute to metabolic dysfunction. Excessive blue light exposure may even be linked to more rapid aging and brain damage, based on early studies on flies.

You can take steps to minimize your exposure, including wearing blue light glasses in the evening and turning off digital screens two hours before bed each night.

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