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Updated November 3, 2020

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Medically Reviewed by

Dr. Abhinav Singh

author

Written by

Rob Newsom

Many of us reach for a computer or smartphone after getting into bed. In fact, the 2011 National Sleep Foundation’s Sleep in America poll found that 90% of Americans report using an electronic device in their bedroom within an hour of trying to fall asleep.

Unfortunately, screens on these devices can emit blue light that interferes with our natural sleep cycles. Decreasing exposure to light in the evening, and blue light, in particular, is an important way to help your body naturally prepare for sleep.

What is Blue Light?

Light is composed of electromagnetic radiation, which is an invisible form of energy. Our eyes interpret colors of light based on the amount of energy they contain. Rainbows show us the entire spectrum of visible light. White light, like the light emitted by the sun, is the combination of all the colors of the visible light spectrum.

Blue light is a portion of the visible light spectrum that can have unique effects on alertness, hormone production, and sleep cycles. This wavelength of light is emitted by LED and fluorescent lights, as well as many electronic devices.

How Does Blue Light Affect Sleep?

Circadian rhythms are finely-tuned, 24-hour cycles that help our bodies know when to carry out essential functions. Light is the most important factor in aligning circadian rhythms and, for much of human history, these rhythms were closely aligned with sunrise and sunset.

With the advent of artificial light and electronics, people are being exposed to increasing amounts of light before bedtime. While all types of visible light can affect circadian rhythms, blue light has the largest impact.

We get the most of our exposure to blue light from the sun. Blue light stimulates parts of the brain that make us feel alert, elevating our body temperature and heart rate. During the day, blue light can improve performance and attention, tuning our circadian rhythm and setting us up for a better night’s sleep after the sun sets.

Properly-timed exposure to blue light can treat several sleep disorders. Circadian rhythm disorders like occur when a person’s circadian rhythms aren’t in alignment with their environment. Light therapy, and blue light in particular, can help realign the body’s circadian rhythms and improve sleep.

Blue light suppresses the body’s release of melatonin, a hormone that makes us feel drowsy. While this may be helpful during the day, it becomes unhelpful at night when we’re trying to sleep. Being exposed to blue light in the evening can trick our brain into thinking it’s still daytime, disrupting circadian rhythms and leaving us feeling alert instead of tired.

Chronic misalignment of circadian rhythms can also lead to many negative health impacts, including metabolic disorders and mental health conditions such as depression. With the significant health consequences associated with exposure to blue light after dark, it’s important to understand the sources of blue light and ways to reduce the risks.

What Devices Give Off Blue Light?

Many people work under artificial lights and are constantly interacting with the screens of electronic devices. It’s understandable to want to know which of these sources emit blue light.

Common sources of blue light include:

  • Fluorescent lights
  • LED lights
  • Smartphones
  • Televisions
  • Computer screens
  • Tablets
  • E-readers
  • Video game consoles

The good news is that the risks of nighttime blue light exposure can be reduced through relatively simple and fast methods.

Mitigating the Effects of Blue Light

The most effective way to reduce exposure to blue light in the evening is to simply turn off the sources. This means dimming or reducing LED and fluorescent lighting and turning off electronic devices after it gets dark outside.

Specialty glasses may also be helpful in reducing exposure to blue light. While they may not work for everyone, blue-light-blocking or amber glasses can reduce the melatonin-suppressing effects of bright light.

Since many people can’t simply turn off sources of blue light after it gets dark, here are a few other ideas to reduce blue light exposure that may be interfering with your sleep.

  • Make it a routine: Set an alarm that reminds you to turn off electronics 2 to 3 hours before bedtime.
  • Find a better lamp: If you like to read in bed, try getting a lamp that doesn’t emit blue light. Red or orange lamps work well, as does natural lighting like candles.
  • Learn to dim: Find out if you can dim the brightness on your electronic devices or if they have a “night mode” that reduces the emission of blue light.
  • Try an app: If you need to use devices before bed, try out one of several smartphone and computer applications that can help reduce blue light emission.
  • Improve your sleeping environment: If there are light sources in your bedroom that you can’t dim or turn off, try using an eye mask to block them out once you’re in bed.
  • References

    +10 Sources
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    2. 2. Sollars, P. J., & Pickard, G. E. (2015). The Neurobiology of Circadian Rhythms. The Psychiatric clinics of North America, 38(4), 645–665. https://doi.org/10.1016/j.psc.2015.07.003
    3. 3. Division of Sleep Medicine at Harvard Medical School. (2007, December 18). The Drive to Sleep and Our Internal Clock | Healthy Sleep. Retrieved October 27, 2020, from http://healthysleep.med.harvard.edu/healthy/science/how/internal-clock
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