Abstract
Light plays a crucial role in the normal development of the human eye and in the formation of vision. The artificial lighting environment that humans have created is an inevitable outcome of modern societal progress, and artificial illumination is one of the environmental factors implicated in both ocular health and eye injury. As we advance toward AI‑driven lighting technologies, how can we identify research directions that promote optimal eye health? Drawing on comprehensive scientific studies of light and vision, as well as numerous analytical perspectives, the author argues that future AI‑enabled lighting should emulate natural sunlight by carefully tailoring its spectral composition, mimicking the circadian rhythms of daylight, and offering adjustable settings.

Keywords: AI lighting; visual health; natural light

Through long-term observation and research, humans have recognized the critical role of light in the development of human vision, gradually gaining an understanding of the diverse properties of “light”—represented by sunlight—and its profound significance for human progress. Artificial lighting has expanded humanity’s need for well-lit environments, enhancing efficiency in industrialized societies.

Scientific research has established the substantial contribution of artificial lighting to the extension of visual functions essential for human development, and has also begun to elucidate the relationships between artificial lighting, illuminated environments, and illuminated reading surfaces, and the onset and progression of eye health issues—such as the sharp rise in myopia prevalence among adolescents and the trend toward earlier onset of myopia; the steady increase in cases of dry eye and visual fatigue; and age-related macular degeneration, which has become the third leading cause of blindness worldwide.

Meanwhile, research findings suggesting that outdoor activities can mitigate the onset and progression of myopia have rekindled interest in the relationship between light and ocular health. Subsequent studies have shown that the mechanism underlying this effect involves changes in retinal or scleral biomarkers associated with myopia when individuals are exposed to natural daylight.

After synthesizing relevant research, the author contends that although many aspects of natural light remain poorly understood, a future lighting landscape that closely mimics natural light may well represent the path forward for improving eye health. While humanity cannot return to a purely natural era devoid of artificial illumination, the advent of the AI‑driven technological revolution offers significant potential for AI‑enabled lighting to emulate the key characteristics of natural light, thereby addressing visual‑health challenges. Accordingly, the author proposes: in the future, AI‑powered lighting should strive to emulate “sunlight.”

1. Light and Vision

According to historical records, as early as more than 300 years BCE, Aristotle proposed that the essence of natural light is a beam of white light, with color arising from differences in brightness and darkness. In 1672, Newton published his “New Theory of Colors and Light,” arguing that, contrary to Aristotle’s view, natural light is not a simple white light but rather a composite mixture of various colored lights with different refractive indices, a claim he substantiated through prism experiments. In 1690, Huygens advanced the theory that “light may be a wave,” using it to explain the phenomena of refraction and reflection. In 1864, Maxwell, after extensive research, posited that light is an electromagnetic wave perceptible to the human eye, with the visible spectrum spanning only 380–780 nm. We commonly refer to this range of wavelengths as visible light. Depending on their wavelength, visible light can be decomposed into fundamental monochromatic colors, such as red, orange, yellow, green, blue, and others.

The human eye is a light‑sensing organ that evolved under natural illumination. When light enters the eye, the iris automatically adjusts the pupil size to regulate the amount of light reaching the retina. Meanwhile, the ciliary muscles contract and relax, altering the shape and refractive power of the lens to achieve sharp retinal focus. Once light strikes the retina, photoreceptor cells convert the light energy into electrical signals. These signals are sequentially transmitted and processed through neural circuits within the retina, then conveyed via the optic nerve to the visual center of the brain, where they are ultimately analyzed to give rise to vision.

The brightness of light influences human color perception. Color is a subjective sensation elicited by light composed of different wavelengths or spectra, and our perception of color arises from the brain’s neurons interpreting physical parameters such as wavelength in a complex, abstract manner. Color has three primary attributes: hue, lightness, and saturation. In everyday life, extremely high‑energy infrared radiation is visually imperceptible to the human eye; it lacks perceived brightness because retinal photoreceptors are insensitive to it, failing to generate any sense of luminance. Thus, the absolute physical energy of light bears no direct correlation with the brightness we experience. The perceived brightness of a color is modulated by ambient illumination. In 1823, Purkinje observed that under daylight, red and blue flowers of equal lightness appear differently: at twilight, the blue flower seems brighter than the red one. This phenomenon—where color lightness shifts as ambient brightness declines—is known as the Purkinje effect. Since then, artists have skillfully exploited this unique interplay between light and human visual perception to create works that captivate the eye and evoke emotional responses.

To ensure that objects at varying distances and brightnesses are sharply focused on the retina, the human eye adjusts its pupil size, ciliary muscle, and photoreceptor activity. However, when working or studying under excessively bright, dim, or unstable lighting, the eye’s accommodative rate increases and the range of accommodation widens. Prolonged exposure to such rapid and excessive accommodative responses can lead to over‑accommodation, resulting in visual fatigue and even a decline in visual acuity. Although the human eye can perceive an extremely broad range of luminances—spanning from fractions of a nit to several million nits—it cannot simultaneously resolve such an extensive dynamic range. Once the eye has adapted to the average brightness of a given environment, its effective visual range becomes limited.

From the foregoing discussion of the relationship among the human eye, light, and visual changes, it is evident that “the human eye–light–vision and visual response–eye’s adjustment to changes in light” constitutes an extremely sensitive, intricately interwoven, highly precise, and remarkably harmonious automatic regulatory system, enabling humans to develop in a balanced, step-by-step manner within natural environmental conditions.

2. Lighting and Visual Health

After humanity came to understand “light,” it gradually invented the kerosene lamp and the gas lamp, and it was not until 1801 that the first electric light bulb made its debut, marking the dawn of the era of artificial illumination. Artificial lighting maximized the visual capabilities essential for the social progress people had long envisioned, and from that point on, development in this field gained unstoppable momentum.

Scholars have found that the longer people work under incandescent lighting indoors, the greater the impact on their visual health. The flickering of fluorescent lights can lead to eye strain when working under such illumination over extended periods. Incandescent lamps and various electronic devices used indoors can likewise cause eye strain and other serious vision‑related problems. Surveys indicate that more than 83% of Americans spend over two hours per day using electronic devices; among them, 32.6% report symptoms of eye strain, 22.7% experience dry eyes, and 22.0% even complain of blurred vision.

Some scholars argue that the modulation of sensory and neural responses under light stimulation can account for symptoms of visual fatigue observed under typical artificial lighting. Rey found that, compared with high-frequency (100 kHz) illumination, working under low-frequency (50 Hz) fluorescent lighting leads to a substantial reduction in the human eye’s critical flicker fusion frequency (CFF) and requires longer reaction times. In other words, indoor lighting with low‑frequency flicker is more likely to induce visual fatigue and may even increase the likelihood of workplace errors.

When indoors, people should minimize exposure to the LED light emitted by various electronic device screens. The blue light from LEDs is a monochromatic component of visible light with a relatively short wavelength and high energy. Animal studies and some in vivo investigations have shown that, with aging, lipofuscin accumulates in the retinal pigment epithelium, making the retina more susceptible to damage from high‑energy blue light. This can trigger cellular apoptosis and promote the onset and progression of age‑related macular degeneration and other retinal disorders.

Artificial lighting also affects the normal growth and development of the eye. Studies have shown that prolonged exposure of guinea pigs to artificial light with a specific, regular frequency can induce excessive ocular elongation and an increase in myopic refractive error. By artificially altering the lighting frequency, it is possible to disrupt the guinea pig’s normal emmetropization process. Meanwhile, in human in vivo studies, researchers have found that infants who are exposed to fluorescent lighting during nighttime sleep before the age of two are more likely to develop myopia later in life. Consequently, scholars argue that disrupting the natural diurnal lighting cycle can impair ocular growth and development, and that excessive exposure to fluorescent lighting may contribute to axial elongation and the onset of myopia.

3. Insights from New Discoveries on Natural Light and Visual Health

Some scholars argue that excessive near work leads to myopia; however, to date, numerous studies have failed to establish a definitive association between near work and myopia. Consequently, it is believed that, in addition to excessive near work, other significant factors may also contribute to the onset and progression of myopia.

In recent years, researchers have begun to examine the relationship between light exposure and myopia, and numerous studies have demonstrated a strong association between time spent outdoors and the development of nearsightedness. The more time children spend outdoors, the lower their likelihood of developing myopia. According to research, for every additional hour per week that children spend outside, their risk of developing myopia during childhood decreases by 14%.

“Duration of outdoor activities” is an independent protective factor against myopia, a finding that has been consistently replicated in studies conducted by various researchers. In light of these results, we typically explore two avenues—either by hypothesizing further or by conducting more in-depth investigations:
① Its protective effect is correlated with light intensity. Since the intensity of sunlight is typically tens of times greater than indoor lighting, high-intensity illumination can, on the one hand, cause pupillary constriction and increase depth of field, thereby reducing blur and helping to inhibit the onset of myopia.
② It is related to reduced reading or to physical health. Increasing outdoor activities effectively reduces time spent on indoor reading, and a daily dose of outdoor exposure promotes overall health. However, subsequent laboratory studies have revealed a new finding: under natural light, the eye produces dopamine, with stronger illumination leading to greater dopamine release. Dopamine is a chemical believed to regulate normal eye growth and development. When outdoor time decreases, so does the duration of natural-light exposure, resulting in reduced retinal dopamine release. This, in turn, promotes axial elongation, induces retinal defocus, and ultimately contributes to the development of myopia. Thus, an important mechanism by which increased outdoor time can effectively control and slow the progression of myopia lies in the body’s ability, under natural light, to synthesize a specific substance—dopamine.

Natural light can activate mitochondrial cytochrome oxidase in retinal cells, enhancing the retina’s antioxidant capacity. With aging, the gradual accumulation of mitochondrial DNA mutations reduces ATP production and increases the levels of reactive oxygen species in the retina, thereby triggering oxidative stress and a cascade of inflammatory responses. Conversely, reduced exposure to natural light can lead to deficiencies in cytochrome oxidase, potentially precipitating retinal diseases such as age‑related macular degeneration. Studies have shown that near‑infrared light (670 nm), absorbed by mitochondrial cytochrome oxidase, plays a crucial role in mitochondrial repair and in elevating mitochondrial membrane potential, thereby ameliorating age‑related retinal inflammation.

However, natural light also has certain drawbacks. According to some studies, prolonged exposure to sunlight—particularly its ultraviolet radiation—can not only trigger skin diseases but also contribute to the development of pterygium, cataracts, and other ocular conditions. Furthermore, the high‑energy blue light present in natural light is considered a major risk factor for age‑related macular degeneration.

The phenomena examined above invite us to reflect further: the human eye’s needs and reliance on light encompass rhythms related to the “light spectrum,” “intensity,” and “temporal changes.” Undoubtedly, much remains unknown. These crucial natural elements and their underlying patterns of variation have emerged through millennia of evolutionary selection. When the human body encounters them, it initiates a finely tuned self-regulatory process, governing the synthesis, degradation, and dynamic equilibrium of various substances. This intricate interplay and mutual modulation may well underpin the body’s capacity to maintain homeostasis—and, when that balance is disrupted, to re‑establish a new equilibrium.

So, if such a scientific phenomenon were to exist, should we revert to the era of nature? Clearly, that would be an absurd notion. However, if the artificial lighting we rely on could come closer to the qualities of natural light, that might represent a sensible step forward—a return to balance. The advent of artificial intelligence offers hope in this regard.

4. The scientific choices afforded by the development of intelligent artificial lighting

Intelligent artificial lighting will offer us greater scientific flexibility. Once we scientifically identify which components of natural light are beneficial to human eye health, in theory it should be possible to achieve smart artificial lighting that closely mimics natural light by selectively choosing, combining, and dynamically adjusting its parameters.

The spectral composition is an important factor. McColl and Veitch found that, compared with cool white light sources, workers exhibit better visual performance in work environments illuminated by full-spectrum fluorescent lamps. Furthermore, Berman’s research on night‑vision sensitivity suggests that, relative to both cool white and warm white light sources, human night vision is optimal under full‑spectrum daylight‑type lighting.

The relative proportions of different wavelengths of light within the emitted spectrum are also crucial. Blue light can readily trigger age-related macular degeneration and other retinal disorders. Meanwhile, S‑cones and rod cells reach peak sensitivity in blue or bluish‑green environments; these two types of photoreceptors enable us to distinguish blue hues and maintain visibility in low‑light conditions. Consequently, blue light plays an important role in the development of normal color vision and in night vision.

Laboratory studies have shown that reducing blue-light transmission by 50% (at 430 nm) through the use of blue-light‑blocking glasses can decrease photochemical retinal damage by nearly 80%. By leveraging artificial intelligence to dynamically adjust the proportion of blue light in illumination, researchers are seeking an optimal balance that safeguards human visual health. Some scholars have also begun developing AI‑powered lighting systems that mimic natural light while effectively filtering out ultraviolet radiation, enabling people to enjoy a healthy “sunbath” even indoors.

The adjustable nature of AI‑powered lighting benefits people across different age groups. A study involving computer users aged 18–30 and 40–55, all wearing blue‑light‑filtering glasses, found that the glasses had no significant impact on nighttime visual acuity in the 40–55 age group, whereas participants aged 18–30 reported only subtle changes in color perception. Consequently, the adjustability of AI lighting allows it to tailor the blue‑light content of the light spectrum to suit various age groups; for instance, given the potential harm of blue light and its greater sensitivity to disrupting nighttime vision in middle-aged and older adults, AI lighting systems can reduce blue‑light levels more substantially for this demographic than for younger individuals.

Moreover, research indicates that students who are not exposed to short-wavelength visible light in the morning experience a reduction in their melatonin levels, which in turn leads to an average bedtime that is 30 minutes later each night. This underscores the importance of maintaining an appropriate balance of short-wavelength light—such as blue light—in daily exposure for young people.

AI‑powered lighting can adjust light intensity to suit varying needs. In daily life, the required brightness is relatively low, with a broad acceptable range (>75–100 lux), and stability requirements are not particularly stringent. However, prolonged near‑task activities such as studying or working demand higher illumination levels, and the optimal brightness range is narrower—typically around 300 lux.

The adjustable brightness of AI‑powered lighting can meet diverse visual‑health needs in both work and daily life. Natural light at 800–1,000 lx can also stimulate the brain to release serotonin, helping maintain mental alertness without the need for tobacco or caffeine. Moreover, the brightness‑adjustment capabilities of AI lighting help minimize color‑perception errors caused by the Purkinje effect.

Artificial intelligence–based lighting can emulate the 24-hour circadian rhythm of natural light. Research indicates that insufficient exposure to natural light indoors increases feelings of discomfort, whereas appropriate exposure to natural light at the right times and in the right rhythm can help alleviate such discomfort. Beyond daytime brightness, darkness at night also plays a critical role in human health. While simulating the 24-hour circadian patterns of natural light, AI‑powered lighting also accounts for the amplitude and rate of external light variations. Near windows, the natural light entering from outside fluctuates significantly—ranging from hundreds to tens of thousands of lux—particularly during midmorning and late afternoon, as well as on overcast or rainy days. Such rapid and extreme changes in light can be detrimental to work and study.

Therefore, the development of AI‑powered lighting both respects the dynamic nature of natural light and effectively mitigates the visual discomfort caused by its rapid and substantial fluctuations—fluctuations that are often driven by weather and other environmental factors. It is worth noting that the diurnal and even seasonal rhythms of natural light exert a critical influence on human health.

Since the advent of modern society, humans have become inseparable from the convenience and efficiency brought by artificial lighting. Yet, leveraging the revolutionary advances in artificial intelligence, we can align the diverse attributes of artificial illumination with those of natural light—bringing them ever closer to “sunlight.”

Moving closer to “sunlight” does not simply mean reverting to the original spectral composition and luminance variations of natural sunlight; rather, it involves establishing a more harmonious relationship between humans and nature, grounded in research on the health‑promoting connections between sunlight and the human eye.