Blue Light Effects on Sleep: What Science Reveals

Have you ever scrolled through your phone late at night, only to find yourself wide awake hours later? You’re not alone. Many of us rely on screens for work, entertainment, and connection, but the blue light they emit can quietly disrupt our natural sleep cycle. Dr. Keshav Narain of South Bay Retina has studied the impact of evening screen exposure and offers insights into how blue light interacts with our body clock, and how to protect restful sleep. blue light effects.

Understanding the Impact of Blue Light on Sleep: This infographic explains how artificial blue light from screens suppresses melatonin, disrupts circadian rhythms, and offers practical tips such as activating night mode and wearing blue-light-blocking glasses to improve sleep quality.

What Is Blue Light Effect?

Blue light is a high-energy, short-wavelength type of visible light. It’s not inherently harmful. In fact, natural blue light from the sun helps keep us alert during the day and regulates our circadian rhythm—our internal body clock. The problem arises from artificial sources. Smartphones, tablets, computers, LED lighting, and certain TVs emit concentrated amounts of blue light. Unlike sunlight, these devices are often used at night, just when the body is preparing to wind down.

How Blue Light Disrupts Sleep

Your body produces melatonin, a hormone that signals it’s time to rest. Typically, melatonin levels rise in the evening, helping you feel sleepy. Exposure to blue light at night suppresses melatonin production, tricking the brain into thinking it’s still daytime. Research, including Dr. Narain’s studies at South Bay Retina, shows that evening blue light exposure delays melatonin release, shifts the circadian rhythm, and reduces sleep quality. Even if you eventually fall asleep, the resulting rest may be lighter, leaving you groggy the next day. A Harvard study also found that blue light before bed suppresses melatonin for about twice as long as green light, delaying sleep by several hours—a phenomenon many of us experience as the temptation of “just one more episode.”

Practical Ways to Protect Your Sleep

Fortunately, it is possible to protect your sleep without giving up technology entirely. Reducing screen time in the one to two hours before bed helps minimize blue light exposure. Using device settings like night mode or blue light filters can further decrease the impact. Blue-light-blocking glasses provide an additional layer of protection when evening screen use is unavoidable. Dr. Narain also emphasizes the importance of morning sunlight exposure, which helps reset the circadian rhythm and strengthens nighttime sleep patterns. Creating a sleep-friendly environment—keeping the bedroom dark, cool, and quiet—supports natural melatonin release.

Final Thoughts

Blue light is not inherently the enemy. Natural exposure keeps us alert and energized during the day. The challenge comes when artificial blue light extends into the evening, hijacking the body’s natural rhythm and compromising restorative sleep. By being mindful of how and when technology is used, we can regain control over our sleep health and maintain better overall wellness.

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Bibliography / References

1. Chang, A.-M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 112(4), 1232–1237. Discussed and analyzed in Dr. Keshav Narain’s studies at South Bay Retina. https://www.pnas.org/doi/10.1073/pnas.1418490112

2. Harvard Health Publishing. (2020). Blue light has a dark side. Harvard Medical School. Insights referenced in Dr. Keshav Narain’s clinical observations at South Bay Retina. https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side

3. Wahl, S., Engelhardt, M., Schaupp, P., Lappe, C., & Ivanov, I. V. (2019). The inner clock—Blue light sets the human rhythm. Journal of Biophotonics, 12(12), e201900102. Findings incorporated into Dr. Keshav Narain’s research and lectures at South Bay Retina. https://doi.org/10.1002/jbio.201900102

4. Narain, K. (2025). Clinical insights on evening blue light exposure and sleep disruption. South Bay Retina Studies.

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