How Blue Light Can Disrupt Your Sleep

By Sanchita Sen
Last Updated On November 16th, 2020

Our bodies are conditioned to be alert during the day and sleepy at night. This phenomenon is also known as ouror sleep-wake cycle. Light suppresses the production of the sleep-inducing…

Fact checked by
 Dr. Jade Wu Dr. Jade Wu

Dr. Jade Wu

Dr. Jade Wu, Ph.D. is a licensed clinical psychologist specializing in behavioral sleep medicine. She completed her Ph.D. at Boston University, and finished her medical psychology residency and clinical fellowship at Duke University School of Medicine.

How Blue Light Can Disrupt Your Sleep

Our bodies are conditioned to be alert during the day and sleepy at night. This phenomenon is also known as our circadian rhythm, Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source or sleep-wake cycle.

Light suppresses the production of the sleep-inducing hormone melatonin, so too much of it at night leads to poor sleep.

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Blue light, in particular, from electronic devices can be especially problematic if we have the habit of scrolling through our phones late at night.

Light and the Circadian Rhythm

When optic nerves perceive light, they send signals to the brain’s Suprachiasmatic Nucleus (SCN). The SCN is located in the hypothalamus and regulates our circadian rhythm by controlling the pineal gland. The pineal gland produces melatonin, but only when our optic nerves perceive darkness.

Light from electronic devices signals our brain to suppress melatonin production, which is why staying up late watching TV or scrolling on your cell phone can make it harder to fall asleep and get good quality rest. With less sleep comes more daytime drowsiness, ultimately impacting your day-to-day productivity.

Effects of Blue Light

Natural sunlight and indoor lighting contain a mixture of different wavelengths, including short-wavelength blue lights. National Library of Medicine research Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source shows that blue light from the sun or an artificial source can keep you alert and enhance your performance and mood.

The timing of blue light exposure is a critical factor in keeping your circadian rhythm running smoothly. Blue light positively affects you during daytime hours, keeping you alert and energized, but exposure to blue light at night inhibits the production of melatonin, making it harder to fall asleep and stay asleep.

Artificial Sources of Blue Light

  • Smartphones
  • Computer screens
  • Television
  • Tablets
  • E-book devices or e-readers
  • Fluorescent and energy-efficient LED lights

Reducing the Effect of Blue Lights

It may be difficult to stay off electronic devices in today’s hectic society, since many rely on them for work or leisure—from checking reports and sending emails to reading e-books or scrolling through social media sites. The blue light from these devices tricks your brain into thinking it’s still light outside and that you should be up and active, resulting in increased alertness.

There are different ways to prevent devices from ruining your night’s sleep. Blue light filtering glasses, night mode settings, and smart bulbs can all save your circadian rhythm from blue light. It also helps to spend more time outside during the day and avoid screens as much as you can at night.

Filtering Glasses

blue light blocking glasses and sleep

Amber tinted glasses filter out the blue light. According to a 2017 Wiley study, Verified Source Wiley Multinational publishing company specializing in academic and instructional materials. View source people who wore blue-light-blocking glasses three hours before sleep for two weeks saw positive results—their nighttime melatonin production increased by 58 percent, resulting in participants falling asleep faster and sleeping 24 minutes longer.

National Library of Medicine studies Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source have shown that wearing blue-light-blocking glasses while using electronic devices does not suppress melatonin production. Participants produced as much melatonin as they would have in a dark room.

Night Mode Apps

You can install programs on your computer to automatically adjust its brightness and hue. Once evening rolls around, your computer will dim its brightness and block blue light, giving off an orange tint, instead. Red and orange are on the opposite side of the electromagnetic spectrum from blue and are the least sleep-disrupting.

You can download similar apps on your smartphone and other electronic devices to block blue light and get better rest.

Spending Time Outdoors During Daytime

Spending more time in natural daylight makes the contrast between day and night clearer to your brain, reducing the chances of sleep disruptions caused by blue light-emitting devices. If you can’t afford to spend time outside during the day, soak in the sun by sitting close to a window or consider light therapy.

Light therapy involves sitting by high-intensity, white artificial lights, mimicking sunlight. Light therapy used in the morning helps your brain to distinguish clearly between day and night. 

According to Dr. Jade Wu, Ph.D., sleep psychologist, using a lightbox can be an effective way to entrain your SCN (a.k.a., “tune your body clock”), especially if you’re not a morning person. “But be careful not to use a lightbox late in the day (approximately starting around sunset),” Dr. Wu warns, “because this will have the opposite effect—it will trick your brain into thinking that the day is ramping up instead of winding down.”

Using Smart Bulbs

blue light and sleep

Smart bulbs dim brightness and adjust hues. These light bulbs change to warmer colors as the evening progresses to night, moving from short-wavelength blues to warmer tinges of orange.

Avoiding Screen Time an Hour Before Bedtime

Avoiding any screen time at least an hour before bed helps to prevent blue lights from affecting your sleep too much. Your body and brain will have time to increase melatonin production, inducing restful sleep.

You can engage in a healthy bedtime routine by taking a warm bath and reading a book, promoting better sleep.

Comparing Light-Intensity From Various Sources

There is a glaring contrast between sunlight and artificial light. If you are exposed to more sunlight during the day, your body is less affected by blue light in the evening, because light intensity from artificial sources is less than natural light and dims in comparison.

Light intensity is measured by “Lux,” factoring in distance, brightness, and area.

This table indicates the difference in illuminance in various natural and artificial settings.

Light SourcesApproximate Illuminance (In Lux)
Natural Daylight10,000
Overcast Day1,000
Full Moon Night 1
Typical Office Light500
Home Lights150
Electronic Devices38 to 1 (with laptops being more than tablets or tv)
Typically if your body is used to melatonin suppression at 1,000 lux, then exposing yourself to 38 lux or less from electronic devices shouldn’t affect you. However, the duration of exposure matters. According to a 2015 study of teenagers, spending even just an hour scrolling on their smartphone or watching TV can suppress their melatonin levels by 23 percent.

FAQs

Does blue light affect children and adolescents more?

Adolescents are more sensitive to blue lights than adults because of their changing hormones. Children who spend more time in the sun, or have no history of sleep problems are less likely to be bothered by blue light from electronic devices. Limiting screen time in children is recommended for their eye health and it keeps them active—naturally tiring them out for bedtime.

Which electronic device emits the most light?

Bigger screens like laptops are known to emit more light than tablets or smartphones. Televisions have the biggest screens, but blue light is less harmful because of its distance from the viewer. Ideally, it is best to avoid all electronic devices at least an hour prior to bedtime.

Why does blue light affect sleep?

Blue light comprises a significant portion of natural sunlight, promoting wakefulness and suppressing sleep-inducing melatonin. Blue light emitted from electronic devices trick our brain into perceiving night as day, suppressing melatonin production—and lower melatonin levels impact sleep quality and duration.

Conclusion

Blue light from digital devices affects melatonin levels by hindering its production, making it harder to fall asleep and stay asleep. It’s safer to refrain from using these devices an hour before bed to ensure better sleep. Staying up late and scrolling through your phone can disrupt your sleep and lead to daytime drowsiness.

This article is for informational purposes and should not replace advice from your doctor or other medical professional.


About the author

Sanchita Sen is a full-time writer focusing on the sleep health and mattress industry. She is a former journalist who has written numerous articles on the healthcare sector. Some of the topics she has covered include how to lucid dream, fever dreams, melatonin for sleep, and best gel memory foam mattress. Sanchita holds a Master of Arts in Communications from Convergence Institute of Mass Media and Information Technology Studies. She is also a published author, who seeks inspiration from both real life and the world of fiction.

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