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Can Blue Light Interfere With Sleep?

Can Blue Light Interfere With Sleep?
Danil Nevsky/Stocksy
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Updated on April 8, 2025
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Our smartphones, computer screens, televisions, the fluorescent lights in the office, and the sun all emit blue light. And experts want you to know that yes, exposure to blue light does affect sleep.

Read on to learn how blue light impacts sleep, how blue light therapy can treat sleep disorders, and what you can do to optimize your blue light exposure and improve your sleep quality.

What Is Blue Light?

Blue light is part of the spectrum of light the human eye can see and has the second shortest wavelength (after indigo and violet) and most energy. Colors on the other end of the light spectrum — red and orange, for example — have longer wavelengths and less energy. Light in this frequency range makes up around one-third of all visible light.

The most significant sources of blue light exposure on Earth are the sun’s rays. However, electronic screens, such as those on televisions, smartphones, tablets, computers, and e-readers, also emit blue light, as do light-emitting diode (LED) lights and fluorescent light bulbs.

How Does Blue Light Affect the Brain and Body Clock?

Blue light has a direct impact on our brains and body clocks.

 Blue light from the sun, for instance, helps keep our circadian rhythm on schedule (aligned).

Circadian rhythms are the changes to behavior and physical and mental function that an organism goes through in roughly a 24-hour cycle. The most crucial factors in controlling circadian rhythms are light and dark, but your sleep cycle, appetite, digestion, body temperature, and hormone levels all play critical roles.

Part of the brain called the hypothalamus keeps your circadian rhythm in sync, especially a small cluster of cells called the suprachiasmatic nucleus (SCN).

Is Blue Light Making Your Sleep Worse?

The brain doesn’t distinguish between blue light from the sun and blue light from sources like our cellphones and laptops, so blue light at bedtime can signal to the brain that it’s time to be awake.

“It essentially tricks the brain into thinking it’s daytime in the evening and suppresses the mechanisms that promote sleep,” says Phillip Yuhas, PhD, an assistant professor at the Ohio State University College of Optometry in Columbus.

Research from the past decade suggests that exposure to artificial blue light in the evening tends to make sleep worse.

For instance, a study published in 2014 found that people who read e-books before bedtime were more tired the next day compared with people who read traditional books. Those who looked at e-readers had shorter rapid eye movement (REM) sleep, a deeper sleep state when key brain regions consolidate memory.

Dr. Yuhas recognizes that e-books have come a long way since this study. Many more now offer “night shade modes” that research has shown may reduce short-wavelength light like blue light. While clinical trials need to replicate these findings, the evidence suggests that screen-dimming can relieve but not fully prevent sleep disruption.

 “I still believe that the best option for patients is no screens before bed, however,” Yuhas says.
Several studies suggest that blue light disrupts the production of melatonin, a hormone the brain naturally produces to signal readiness for sleep.

Melatonin levels naturally start to rise in our bodies about two hours before we fall asleep, and remain high while we’re sleeping. But exposure to light — especially blue light — during this time may interrupt the natural production of melatonin, making it harder to fall asleep and stay asleep.

 In one study, blue light suppressed melatonin secretion for twice as long as the immediately longer green wavelength of light.

A person’s age may influence how they react to blue light. For instance, some studies have found that younger adults tend to be more sensitive to light changes than older ones.

It’s important to note that research on blue light and sleep often has limitations that make it difficult to generalize findings. Studies tend to be relatively small and cover only short periods of time.

Blue Light Exposure in the Daytime

Blue light tells the body to wake up, boosting mood, reaction speed, and attention.

 In the morning and throughout the day, that can be helpful.

“Light exposure when you wake up can help you when you have jet lag or need to reset your body’s natural circadian rhythms just like light right before bedtime disrupts that process,” Yuhas says.

Yuhas says blue light tells the hypothalamus that it’s morning. In the same way that at night, blue light signals the brain that it’s time to be awake, in the morning, blue light exposure shuts off melatonin production in the brain. This essentially means shutting off the signal from the brain telling the body to be asleep.

 This may support increased alertness after waking up, and blue light exposure can provide a much needed mood and focus boost during the day.

For example, a study exposed 12 astronauts on the International Space Station to an hour of red-enriched or blue-enriched light when the researchers woke them up after five minutes of slow-wave sleep, or deep sleep.

 During this hour, the astronauts reported feeling more alert and cheerful and less depressed and sleepy after blue-light exposure than red-light exposure.

Studies have produced mixed results on exactly how blue light affects mood.

How Does Blue Light Therapy Help With Sleep Disorders?

Artificial blue light is used to treat a number of conditions, including insomnia, via exposure to a light therapy box or lamp that emits bright light that mimics natural sunlight. Typically, patients keep the light box close to them (about 24 inches away) so the light is in their peripheral vision. Generally speaking, mornings are better for treatment.

Blue light therapy may also help with circadian rhythm–related sleep issues, such as jet lag and changes in sleep schedule due to shift work.

 It’s also suitable for treating delayed sleep phase syndrome (a disorder that makes falling asleep until the early hours of the morning challenging) and advanced sleep phase syndrome (a disorder that makes it difficult to stay awake in the early evening while waking up too early in the morning).

Consistent blue light therapy can help with all these circadian rhythm-related sleep issues, by gradually adjusting your sleep schedule, and resetting your circadian rhythm. About 30 minutes of light therapy lamps in the mornings can promote wakefulness earlier, and help someone adjust to an earlier daily bedtime, and light exposure in the evenings can help someone push their bedtime later.

Some people turn to a light box as an alternative light source for overcast days or during the winter months to combat seasonal affective disorder (SAD). If you’re looking for a light box, the Sleep Foundation recommends one with a bright broad spectrum of light, between 2,500 to 10,000 lux.

How to Manage Blue Light Exposure for Better Sleep

Here’s how and when to expose yourself to blue light throughout the day to feel more alert, and what to know about shutting things down at night for our best shuteye.

Get Your Fill of Daytime Light Exposure

Start your day with sunlight — or bright light — to set the tone for the day and help promote wakefulness and alertness. Sitting near a window on a sunny day is enough to maintain alertness, Yuhas says. Even on a cloudy day, you should still aim to get some outdoor light, which provides more blue light than your computer screen.

Limit Exposure to Screens for 1 Hour Before Bedtime

Yuhas recommends establishing a technology curfew by stashing away all electronic devices for the evening about one hour before lights out. Turn to other activities that may help with winding down, like reading a book, working on a puzzle, stretching, or meditation.

Adjust the Settings on Your Devices

If putting away your smartphone isn’t feasible, Yuhas recommends shifting the setting to “night mode,” “dark mode,” or another option that dims the brightness.

When to Speak to a Doctor

If you have difficulty falling asleep or feelings of fatigue or distraction during the day that occur at least three times a week and linger for at least three months, chronic insomnia may be at play. If your sleep difficulties bother you or interfere with your everyday activities, contact your primary care doctor or schedule an appointment with a sleep specialist.

The Takeaway

  • The sun is the main source of blue light, but devices like cellphones and e-readers also give off blue light.
  • Blue light can boost mood and alertness during the day, but blue light at night may increase the risk of sleep issues.
  • Blue light therapy, prescribed by a healthcare professional, may help treat insomnia and other circadian rhythm disorders.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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  2. Blue Light: What It Is and How It Affects Sleep. Sleep Foundation. January 12, 2024.
  3. Circadian Rhythms. National Institute of General Medical Sciences. September 2023.
  4. Van Drunen R et al. Circadian Rhythms of the Hypothalamus: From Function to Physiology. MDPI Clocks & Sleep. February 25, 2021.
  5. Chang AM et al. Evening Use of Light-emitting EReaders Negatively Affects Sleep, Circadian Timing, and Next-morning Alertness. PNAS. September 24, 2014.
  6. Evaluation of Two Strategies for Alleviating the Impact on the Circadian Cycle of Smartphone Screens. Optometry and Visual Science. March 2020.
  7. Alam M et al. Impacts of Blue Light Exposure From Electronic Devices on Circadian Rhythm and Sleep Disruption in Adolescent and Young Adult Students. Chronobiology in Medicine. March 29, 2024.
  8. Should You Be Worried About Blue Light? American Academy of Ophthalmology. March 10, 2021.
  9. Blue Light Has a Dark Side. Harvard Medical School. July 24, 2024.
  10. Westwood E et al. The Effects of Light in Children: A Systematic Review. Journal of Environmental Psychology. August 2023.
  11. Souza de Toledo LH et al. Modeling the Influence of Nighttime Light on Melatonin Suppression in Humans: Milestones and Perspectives. Journal of Photochemistry and Photobiology. August 2023.
  12. Sleep Phases and Stages. National Heart, Lung, and Blood Institute. March 24, 2022.
  13. Hilditch CJ et al. Blue-enriched Light Improves Alertness and Mood Following Abrupt Awakening from Slow Wave Sleep. NASA Technical Reports Server. February 4, 2021.
  14. Silvani MI et al. The Influence of Blue Light On Sleep, Performance and Wellbeing in Young Adults: A Systematic Review. Frontiers in Physiology. August 16, 2022.
  15. Light Therapy for Insomnia Sufferers. Sleep Foundation. November 16, 2023.
  16. Hester L et al. Evening Wear of Blue-blocking Glasses for Sleep and Mood Disorders: A Systematic Review. Chronobiology International. May 24, 2021.
  17. Delayed Sleep Phase Syndrome. Cleveland Clinic. October 13, 2023.
  18. Treatment for Advanced Sleep Phase Syndrome. Stanford Medicine.
  19. Diagnosing Insomnia. Sleep Foundation. December 22, 2023.
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Abhinav Singh, MD

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Abhinav Singh, MD, is a board-certified sleep medicine specialist and the medical director of the Indiana Sleep Center. He is also an associate clinical professor at Marian University College of Osteopathic Medicine in Indianapolis, where he developed and teaches a sleep medicine rotation.

Dr. Singh’s research and clinical practice focus on sleep disorders, including excessive daytime sleepiness, narcolepsy, sleep apnea, insomnia, and sleep education.

Singh is a peer reviewer for the Journal of Clinical Sleep Medicine, Sleep Health (from the National Sleep Foundation) and the Journal of Sleep Disorders: Treatment and Care, and is coauthor of the book Sleep to Heal: 7 Simple Steps to Better Sleep. He has received several Top Doctor recognitions and is the sleep specialist for the Indiana Pacers NBA team.

He lives in the Indianapolis area and enjoys music production and racquet sports.

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Adam is a freelance writer and editor based in Sussex, England. He loves creating content that helps people and animals feel better. His credits include Medical News Today, Greatist, ZOE, MyLifeforce, and Rover, and he also spent a stint as senior updates editor for Screen Rant.

As a hearing aid user and hearing loss advocate, Adam greatly values content that illuminates invisible disabilities. (He's also a music producer and loves the opportunity to explore the junction at which hearing loss and music collide head-on.)

In his spare time, Adam enjoys running along Worthing seafront, hanging out with his rescue dog, Maggie, and performing loop artistry for disgruntled-looking rooms of 10 people or less.

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