Let’s face it: screens are here to stay. You are reading these words on a screen even now, just as I am (once the little voices in my head tell my fingers what to type).

And, we’re not alone. It is estimated that most Americans spend at least five hours per day just on a smartphone screen, with millennials logging an eye-popping 11 hours! And on average we check our phones an astonishing 150 times a day - impacting our eye, skeletal, and hormonal health - to say nothing of the impact on our mental health and social behavior.

But like it or not, life has gone online. And in a post-COVID-19 landscape, anyone wishing to stay connected (or employed) will likely have to adapt to more screen exposure - not less.

So what’s a modern human to do?

Blue skies, smiling at me

First, some optics. “Blue light” from a physiological perspective, does not necessarily look “blue.” It can present as basically any color, including the mostly white screen you are looking at now.

Physicists call light from screens “blue” because in contrast to natural sunlight, which is the kind of light with which we evolved, light from screens contains much more of the blue wavelength than does normal sunlight.

Blue sky with white clouds
The blue light that heals body and soul is found in blue skies.

Second, truly blue light has a lot of perks - the biggest and most beautiful? That amazing big blue phenomenon you see on a beautiful sunny day: the sky! 

When electromagnetic light waves travel through space and react with our atmosphere, the blue waves, shorter and choppier, scatter more than any other wavelength color, making the whole sky appear blue (Sliney, 2016).

And while blue light gets plenty of negative press, blue light therapy holds promise of clinical benefit for a range of disorders including topical skin conditions (Scott, 2019), post-traumatic brain injury complications (Quera Salva, 2020), and wound healing (Adamskay, 2011) as well as promoting wakeful and alertness in students (Choi, 2019).

The rainbow connection

Sunlight, like all white or “visible” light, contains all the colors of a rainbow. In fact, the spectrum of visible color can be seen clearly in a rainbow, when the separate red, orange, yellow, green, blue, indigo and violet colors are reflected through rain droplets (Gedzelman, 2008).

Blue, indigo, and violet rays, on the shorter end of the spectrum, are the choppier waves of visible light, followed by ultraviolet light, which human eyes cannot see (but bees can!) (Horridge, 2016).

Those shorter, choppier light wavelengths that make a bright, sunny sky appear blue are sending the “It’s daytime!”  message loud and clear to a very important recipient: your hypothalamus.

What’s all the fuss about my hypothalamus?

A tiny but crucial region near the center of the brain, your hypothalamus is like command central for hormonal-related signals. It produces releasing and inhibiting hormones, which boss around the other hormones in the body. It also helps to set your circadian rhythms. If your body were a cruise ship, the hypothalamus would be the director: it tells everybody when to eat, when to sleep, and when to close the buffet (appetite regulation) (Asuka, 2021).

When your hypothalamus registers blue light, it suppresses melatonin production - the hormone that makes us feel sleepy. Blue light stops, melatonin production starts (Skene, 2006). Pretty straightforward formula. Except, instead of getting blue light during the day, from the sun, and then stopping once it sets, we now get just as much (sometimes more) blue light at night, from screens on electronic devices (Arjmandi, 2018).

The blue light special

As humans spend more time indoors and online, we increasingly replace our sunshine with screen time. Blue light wavelengths are the “are the strongest synchronizing agent for the circadian system that keeps most biological and psychological rhythms internally synchronized” (Wahl 2019). Translation: nothing makes our body clock tick quite as strongly as those blue light waves sending their “wake-up” message to our brains.

So even though blue light can do a lot of good, at the wrong moment, it can send the wrong message to your body. And some of those messages can be far more damaging than inopportune wakefulness, such as the hormone-dependent cancers to which excess blue light exposure has been linked (Garcia-Saenz, 2018), along with the photoreceptor damage it can hasten in eye tissue (Tosini, 2016).

Don’t get the blue light blues

Woman holding fish up to face
Fish are great for eye health, but don’t apply topically. Eat them.

Now, the good news: Maintaining a high omega-3 intake from wild-caught seafood is a slam-dunks for maintaining eye health. Not only do omega-3s promote inflammation-resolving signals, “they protect against oxidative induced apoptosis [cell death] in the retina” as well as myriad other benefits beyond eye wellness (Schweigert, 2010).

But what about the other potential downsides of overdoing blue light?

One quick and easy fix is to have a “no-screen” rule after a certain time of night, especially for children and young adults, whose bodies and hormones are still developing. (I don’t recommend trying this on your family for the first time unless you are armed with a bottle of wine and an analog novelty like Legos or a new board game. Or a soundproofed room).

Adopting other simple habits, like wearing blue-light blocking glasses while viewing screens, or increasing warm tones on your devices (by, for example, using downloadable software called f.lux) can also reduce blue light intake.

Bottom line

Blue light excess is a fact of modern life that requires careful management to keep that spring in your step. Balancing screen time is a major factor in lessening exposure to blue light, so don’t feel bad about stepping away from the screen for your health from time-to-time… after, of course, you make sure you’re stocked up on wild-caught seafood!

 

References

Adamskaya, N., Dungel, P., Mittermayr, R., Hartinger, J., Feichtinger, G., Wassermann, K., Redl, H., & van Griensven, M. (2011). Light therapy by blue LED improves wound healing in an excision model in rats. Injury, 42(9), 917–921. https://doi.org/10.1016/j.injury.2010.03.023

Arjmandi, N., Mortazavi, G., Zarei, S., Faraz, M., & Mortazavi, S. (2018). Can Light Emitted from Smartphone Screens and Taking Selfies Cause Premature Aging and Wrinkles?. Journal of biomedical physics & engineering, 8(4), 447–452.

Choi, K., Shin, C., Kim, T., Chung, H. J., & Suk, H. J. (2019). Awakening effects of blue-enriched morning light exposure on university students' physiological and subjective responses. Scientific reports, 9(1), 345. https://doi.org/10.1038/s41598-018-36791-5

Garcia-Saenz, A., Sánchez de Miguel, A., Espinosa, A., Valentin, A., Aragonés, N., Llorca, J. Amiano, P., Martín Sánchez, V., Guevara, M., Capelo, R., Tardón, A., Peiró-Perez, R., Jiménez-Moleón, J. J., Roca-Barceló, A., Pérez-Gómez, B., Dierssen-Sotos, T., Fernández-Villa, T., Moreno-Iribas, C., Moreno, V., García-Pérez, J., … Kogevinas, M. (2018). Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study). Environmental health perspectives, 126(4), 047011. https://doi.org/10.1289/EHP1837

David Gedzelman S. (2008). Simulating rainbows in their atmospheric environment. Applied optics, 47(34), H176–H181. https://doi.org/10.1364/ao.47.00h176

Horridge A. (2016). Parallel inputs to memory in bee colour vision. Acta biologica Hungarica, 67(1), 1–26. https://doi.org/10.1556/018.67.2016.1.1

Quera Salva, M. A., Azabou, E., Hartley, S., Sauvagnac, R., Leotard, A., Vaugier, I., Pradat Diehl, P., Vallat-Azouvi, C., Barbot, F., & Azouvi, P. (2020). Blue-Enriched White Light Therapy Reduces Fatigue in Survivors of Severe Traumatic Brain Injury: A Randomized Controlled Trial. The Journal of head trauma rehabilitation, 35(2), E78–E85. https://doi.org/10.1097/HTR.0000000000000500

Rohringer, S., Holnthoner, W., Chaudary, S. et al. The impact of wavelengths of LED light-therapy on endothelial cells. Sci Rep 7, 10700 (2017). https://doi.org/10.1038/s41598-017-11061-y

Schweigert, F. J., & Reimann, J. (2011). Mikronährstoffe und ihre Bedeutung für das Auge--Wirkungsweise von Lutein/Zeaxanthin und Omega-3-Fettsäuren [Micronutrients and their relevance for the eye--function of lutein, zeaxanthin and omega-3 fatty acids]. Klinische Monatsblatter fur Augenheilkunde, 228(6), 537–543. https://doi.org/10.1055/s-0029-1245527

Shahid, Z., Asuka, E., & Singh, G. (2021). Physiology, Hypothalamus. In StatPearls. StatPearls Publishing.

Skene, D. J., & Arendt, J. (2006). Human circadian rhythms: physiological and therapeutic relevance of light and melatonin. Annals of clinical biochemistry, 43(Pt 5), 344–353. https://doi.org/10.1258/000456306778520142

Sliney D. H. (2016). What is light? The visible spectrum and beyond. Eye (London, England), 30(2), 222–229. https://doi.org/10.1038/eye.2015.252

Tosini, G., Ferguson, I., & Tsubota, K. (2016). Effects of blue light on the circadian system and eye physiology. Molecular vision, 22, 61–72.

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. https://doi.org/10.1002/jbio.201900102

West, K. E., Jablonski, M. R., Warfield, B., Cecil, K. S., James, M., Ayers, M. A., Maida, J., Bowen, C., Sliney, D. H., Rollag, M. D., Hanifin, J. P., & Brainard, G. C. (2011). Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans. Journal of applied physiology (Bethesda, Md. : 1985), 110(3), 619–626. https://doi.org/10.1152/japplphysiol.01413.2009