Hello everyone, this is a homework that I wrote for my “Design as a Science” class. It should be seen as a scientific paper, that covers a serious approach to a given problem. Because of some sleep issues in the past, a love for biology and some physics, this is what I came up with. Enjoy reading!
Abstract
Many people in western civilized cultures are exposed to a number of artificial light sources nowadays. These are mainly used indoors, in urban areas during dark times of the day, on the screens of digital devices, or generally anywhere where light is required. This is of course something with a positive connotation, which does not require any further observation. But the design of artificial lights is often reduced to the subjective well-being of people. One tries to orientate oneself to the fact that the color temperature and brightness of a light source is considered to be appropriate. So-called “white” light, in which the wavelengths of the primary colors red, green and blue occur in equal proportions, has a “hard” character here, for example, and seems to have a more concentrating effect on people, whereas “warm” light with higher red proportions in the composition seem to spread a rather pleasant and relaxing atmosphere.
In fact, our seemingly subjective sensation is due to biological mechanisms. In the eye there are various receptors that are responsible for the perception of visual images, the rods and cones, as well as photosensitive ganglion cells, which seem to focus on the perception of the intensity of the incoming lights, as well as the regulation of our circadian rhythm. “Circadian photoentrainment is the process by which the brain’s internal clock becomes synchronized with the daily external cycle of light and dark. In mammals, this process is mediated exclusively by a novel class of retinal ganglion cells that send axonal projections to the suprachiasmatic nuclei (SCN), the region of the brain that houses the circadian pacemaker.” (Brown RL, Robinson PR. Melanopsin–shedding light on the elusive circadian photopigment. Chronobiol Int. 2004 Mar;21) These specific photoreceptors in mammals have been oriented towards the position of the sun for thousands of years. As a result, today’s people who are constantly exposed to light are threatened with a disruption of this natural unit, since these cells are not able to differentiate between artificial light sources and natural ones, meaning the sun. This can have devastating effects on a person’s mental and physical health. “Abnormalities in this intricate circadian orchestration may alter sleep patterns and contribute to the pathophysiology of affective disorders.” (Rosenwasser AM, Turek FW. Neurobiology of Circadian Rhythm Regulation. Sleep Med Clin. 2015 Dec;10(4):403-12.) In the following I will explain what the more precise connection between our light-seeing behavior, our sleeping and waking phases, as well as our resulting health is.
Scope
Nowadays it can be said with great certainty that our organism represents a complex symphony of all possible biological processes. One organ system is connected to a number of others and their functions are interdependent. For our discourse it must be taken into account that the quality and duration of our sleep is a decisive factor for our health and has serious effects on it in all possible respects. It is now assumed in medicine that our sleep behavior is sometimes the most important influence on our mental and physical health and regeneration. “The shorter your sleep, the shorter your life. The leading causes of disease and death in developed nations—diseases that are crippling health-care systems, such as heart disease, obesity, dementia, diabetes, and cancer—all have recognized causal links to a lack of sleep.” “Sleep is the single most effective thing we can do to reset our brain and body health each day — Mother Nature’s best effort yet at contra-death.” (Walker, Matthew. Why We Sleep. Penguin Books, 2018.)
In fact, humans are creatures who often, voluntarily or involuntarily, seem to be chronically and constantly deprived of sleep. There are many reasons why the quality and quantity of our sleep and therefore our health can be affected. The fact that we lose sight of the homeostasis of our circadian rhythm or neglect it due to artificial light sources is one of the less well-known considerations. “Exposure to Artificial Light At Night (ALAN) results in a disruption of the circadian system, which is deleterious to health. (Touitou Y, Reinberg A, Touitou D. Association between light at night, melatonin secretion, sleep deprivation, and the internal clock: Health impacts and mechanisms of circadian disruption. Life Sci. 2017 Mar 15;173:94-106.)“
These disorders, which are largely voluntary, occur in our societies mostly as a result of habits and cultural phenomena, which we perceive as mentally exhausting and which are shifted to the end of the day due to a greater feeling of free time. We’re talking about activities like watching a series or a movie, getting involved in social media, or anything else that happens on a screen. “Longer average screen-times during bedtime and the sleeping period were associated with poor sleep quality, decreased sleep efficiency, and longer sleep onset latency.” (Christensen MA, Bettencourt L, Kaye L, Moturu ST, Nguyen KT, Olgin JE, Pletcher MJ, Marcus GM. Direct Measurements of Smartphone Screen-Time: Relationships with Demographics and Sleep. PLoS One. 2016 Nov 9;11)
It is largely inevitable not to negatively influence one’s organism with such habits: “In the evening, as it becomes dark outside, melatonin levels rise and body temperature lowers. Melatonin stays elevated throughout the night, promoting sleep. As long as our eyes perceive light, the SCN responds by suppressing melatonin production.” (Dr. Anis Rehman, Sleep Drive and Your Body Clock, Sleep Foundation, January 29, 2021)
The consequence is a correspondingly damaged rhythm or impaired sleep quality due to the resulting lack of melatonin over the night. The light in the morning, the beginning of the day, has a higher proportion of blue. Our biological association “memorized” this over the course of evolution. The aforementioned suprachiasmatic nucleus lets the rest of our organism know that it is broad daylight. “Each morning, as sunlight creeps in, our body temperature begins to rise and cortisol is released, increasing our alertness and causing us to wake up.” (Dr. Anis Rehman, Sleep Drive and Your Body Clock, Sleep Foundation, January 29, 2021)
It is now widely known to the general public that the blue, short-waved region of the light spectrum is most likely to influence the homeostasis of our rhythm. “It has also been reported that shorter wavelengths of light preferentially disturb melatonin secretion and cause circadian phase shifts, even if the light is not bright.” (Cho Y, Ryu SH, Lee BR, Kim KH, Lee E, Choi J. Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment. Chronobiol Int. 2015;32)
It is accordingly correct that the resulting design of our environment has been influenced in a number of ways. Some people have resorted to the use of so-called “blue blockers”, glasses that filter the blue part of the light spectrum. These are largely marketed to people who spend a lot of time in front of the computer and who experience eye pain as a result. This may help some of these people, but it is used in the wrong place for our considerations, since the use of blue light, especially during the day, does not need a generally negative connotation: “The key thing here is that people are hearing a lot nowadays about avoiding blue light. Blue light is so terrible. Well, it turns out that blue light is exactly the wavelength of light that triggers activation of these (retinal ganglion) cells. And that’s exactly what you want early in the day.” “First of all, it triggers the timed release of cortisol, a healthy level of cortisol into your system, which acts as a wake-up signal and will promote wakefulness and the ability to focus throughout the day.” (*)
The appropriate use of such glasses, which is important for us, would therefore rather be during the evening hours. In addition, in many electrical devices that have screens as interfaces, there is now a function to increase the “warmth” of the light, that removes the blue frequencies as well. That seems like a good step in the right direction. However, it is better to have some further caution. As already mentioned, the photosensitive ganglion cells are primarily responsible for the “timing” of our internal clock. These cells are not able to differentiate between the wavelengths of light, but mainly perceive its intensity. “As you approach the evening or nighttime and you want to go to sleep, that is a time to start avoiding bright lights of any color, not just blue light,(…) Dim the lights. If you want to wear blue blockers or do something of that sort, that’s fine.” *(Dr. Huberman Andrew, The Tim Ferriss Show Transcripts: Dr. Andrew Huberman — A Neurobiologist on Optimizing Sleep, Performance, and Testosterone (#521), July 8, 2021)
In addition to understanding how the rhythm is negatively impacted, it is also important to understand how it can be more largely kept in balance:
“It helps to get some sunlight in the late afternoon or evening. Evening light has been shown to help anchor our clocks and encourage the correct level of melatonin, the sleep-inducing hormone.” “We were designed to get a lot of ultraviolet light on our eyes during the day and little during the night,” he said. “The more of these cues to the time of day and night you can give your body, the better off you’ll be” (Erickson Mandy, Setting your biological clock, reducing stress while sheltering in place, Scope Blog Stanford Medicine, June 3, 2020)
Conclusion
It seems that the right way of dealing with light is not too “tangible”. Since this is an area that is not necessarily understood by the general public in its entirety, it is rather difficult to find solutions for these. Our circadian rhythm, the “internal clock” that everyone has in themselves, is based on the light that our eyes can perceive through specific retinal ganglion cells. These convey what time of day it is to all possible processes in the body. (since the rest of the cells in the body have no other ability of their own to “look outside”) These cells direct their activities according to this information. Now, however, the occurrence of artificial light sources disrupts this information and no longer subordinates itself to the actual times of the day. As a result, today’s people with their light-viewing behavior are often busy neglecting their health in a way that no species has been able to do before. Because through the chronic use of artificial light sources at late hours, we effectively throw this internal clock out of balance. It is easy to assume that this can severely affect the harmony between sleeping and waking phases, which leads to a multitude of health complications. These can be determined with both objective and subjective observation. This can lead to a deterioration in the quality of sleep as well as a generally inadequate quantity or duration of sleep. Because when light falls on the eyes, the sleep-inducing and demanding hormone melatonin is suppressed.
People don’t properly get tired, go to bed late and wake up too early because of obligations. The importance of our sleep hygiene seems to be slowly getting into the public, but more active use is required when it comes to spreading the knowledge. It is still not clear that such massive effects exist that sleep deprivation causes. This is the decay of cognitive, physical and psychological sanity. In addition to many generally recognized causes, such as late drinking of caffeinated or alcoholic beverages, a newly found type of influence is the effects of light on our organism. Now there are some things that can be done to counteract this. Filtering out blue light in the evening is a good first step, but beyond that you can design your surroundings in a way that at least simulates the sunset. This means reducing the light intensity and color from their sources if possible and bringing them into the warm/red area.
In addition, it is quite intelligent to get used to a general behavior that respects these findings. That means thinking about activities in the evening that ideally require little or no light. It is certainly worth considering redesigning light sources in urban space afterwards. From a certain time onwards, public transport can change the quality of its lighting in a way that approximates the actual time of day. The same may also apply to facilities that are open around the clock, such as train stations or airports. While it is more difficult to value in public, there are many things that an individual can do for his or her health. It would at least be beneficial for many people who suffer from chronic sleep problems to have access to this knowledge, so it would not be a bad idea to start a campaign in which one creates posters that clarify the core principles of some of the mechanisms mentioned. These can then be hung up in medical centers, for example, or wherever open eyes can capture information.
Thanks for reading, and sleep well.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2376768/
https://pubmed.ncbi.nlm.nih.gov/26568118/
Walker, Matthew. Why We Sleep. Penguin Books, 2018.
https://www.sciencedirect.com/science/article/abs/pii/S0024320517300450?via%3Dihub
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0165331
https://www.sleepfoundation.org/circadian-rhythm/sleep-drive-and-your-body-clock
https://www.tandfonline.com/doi/abs/10.3109/07420528.2015.1073158?journalCode=icbi20
Good work!