Sleep Disturbance From Blue Light

The human circadian rhythm is controlled to a large extent by light, especially light in the blue range. It’s no wonder, then, that we have trouble falling asleep when we look into the strong blue light of our smartphones while we’ re in bed, or when we round off the evening with a movie that flickers blue. Here we briefly summarize what is known about the mechanisms and outline the most exciting studies.

Harvard Medical School
Harvard Medical School

Harvard Informs

The Dark Side of Blue Light

Harvard Medical School is one of the most renowned and prestigious institutions in medical research, and regularly publishes the so-called “Health Letter” on relevant topics.

In July 2020, a comprehensive article on blue light and its effects on our circadian rhythms appeared in this series. We have linked the original article, which we briefly summarize here.

The article mentions various studies showing that the production of the sleep hormone melatonin is disturbed by light, with light in the blue range being particularly impactful.

The text also addresses studies that suggest blue light filters may be a good solution to minimize these effects on the endocrine system.

The following are some of the recommended practices for a good night’s sleep:

-Use red light for night lights, as it has the smallest effect on hormones.

-Avoid looking at screens 2-3 hours before going to bed.

-Use blue light protection glasses when using electronic devices in the evening.

-A lot of bright daylight to be fit and healthy during the day on the one hand, and to be able to fall asleep well in the evening on the other.

Blue Light Sets the Pace for the Internal Clock

This review looks at the effect of light color, intensity, and timing of light irradiation on sleep quality and concludes that even relatively weak blue-spectrum light just before falling asleep has serious effects on circadian rhythms.

Cell Phone Use in the Evening and Sleep Quality

In this study, cell phone use and sleep quality were observed. Those who continued to use their cell phones for at least 30 minutes after turning off the lights had significantly poorer sleep quality, increased daytime sleepiness and took longer to fall asleep.

Blue Light Protection Glasses Help With Insomnia

This randomized study shows, in a small group of subjects with sleep disorders, that wearing blue-light protective eyewear 2 hours before going to bed has a significantly positive effect on sleep duration and quality.

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