Blue-Light Levels Emitted from Portable Electronic Devices Compared to Sunlight

Light-responsive adipose-hypothalamus axis controls metabolic regulation

Light is fundamental for biological life, with most mammals possessing light-sensing photoreceptors in various organs. Opsin3 is highly expressed in adipose tissue which has extensive communication with other organs, particularly with the brain through the sympathetic nervous system (SNS). Our study reveals a new light-triggered crosstalk between adipose tissue and the hypothalamus. Direct blue-light exposure to subcutaneous white fat improves high-fat diet-induced metabolic abnormalities in an Opsin3-dependent manner. Metabolomic analysis shows that blue light increases circulating levels of histidine, which activates histaminergic neurons in the hypothalamus and stimulates brown adipose tissue (BAT) via SNS. Blocking central actions of histidine and denervating peripheral BAT blunts the effects of blue light. Human white adipocytes respond to direct blue light stimulation in a cell-autonomous manner, highlighting the translational relevance of this pathway. Together, these data demonstrate a light-responsive metabolic circuit involving adipose-hypothalamus communication, offering a potential strategy to alleviate obesity-induced metabolic abnormalities.

Do blue light filter applications improve sleep outcomes? A study of smartphone users' sleep quality in an observational setting

Exposure to blue light at bedtime, suppresses melatonin secretion, postponing the sleep onset and interrupting the sleep process. Some smartphone manufacturers have introduced night-mode functions, which have been claimed to aid in improving sleep quality. In this study, we evaluate the impact of blue light filter application on decreasing blue light emissions and improving sleep quality. Participants in this study recorded the pattern of using their mobile phones through a questionnaire. In order to evaluate sleep quality, we used a PSQI questionnaire. Blue light filters were used by 9.7% of respondents, 9.7% occasionally, and 80% never. The mean score of PSQI was more than 5 in 54.10% of the participants and less than 5 in 45.90%. ANOVA test was performed to assess the relationship between using blue light filter applications and sleep quality (p-value = 0.925). The findings of this study indicate a connection between the use of blue light filter apps and habitual sleep efficiency in the 31-40 age group. However, our results align only to some extent with prior research, as we did not observe sustained positive effects on all parameters of sleep quality from the long-term use of blue light filtering apps. Several studies have found that blue light exposure can suppress melatonin secretion, exacerbating sleep problems. Some studies have reported that physical blue light filters, such as lenses, can affect melatonin secretion and improve sleep quality. However, the impact of blue light filtering applications remains unclear and debatable.

Blue light protection factor: a method to assess the protective efficacy of cosmetics against blue light-induced skin damage in the Chinese population

BACKGROUND

Previous studies have shown that visible light (VL), especially blue light (BL), could cause significant skin damage. With the emergence of VL protection products, a harmonization of light protection methods has been proposed, but it has not been widely applied in the Chinese population.

OBJECTIVE

Based on this framework, we propose an accurate and simplified method to evaluate the efficacy of BL photoprotection for the Chinese population.

METHODS

All subjects (n = 30) were irradiated daily using a blue LED light for four consecutive days. Each irradiation dose was 3/4 MPPD (minimum persistent pigmentation darkening). The skin pigmentation parameters, including L*, M, and ITA°, were recorded. We proposed the blue light protection factor (BPF) metric based on the skin pigmentation parameters to evaluate the anti-blue light efficacies of different products.

RESULTS

We found that the level of pigmentation rose progressively and linearly as blue light exposure increased. We proposed a metric, BPF, to reflect the anti-blue light efficacy of products based on the linear changes in skin pigment characteristics following daily BL exposure. Moreover, we discovered that the BPF metric could clearly distinguish the anti-blue light efficacies between two products and the control group, suggesting that BPF is an efficient and simple-to-use metric for anti-blue light evaluation.

CONCLUSION

Our study proposed an accurate and simplified method with an easy-to-use metric, BPF, to accurately characterize the anti-blue light efficacies of cosmetic products, providing support for further development of anti-blue light cosmetics.

Chronic blue light-emitting diode exposure harvests gut dysbiosis related to cholesterol dysregulation

Night shift workers have been associated with circadian dysregulation and metabolic disorders, which are tightly coevolved with gut microbiota. The chronic impacts of light-emitting diode (LED) lighting at night on gut microbiota and serum lipids were investigated. Male C57BL/6 mice were exposed to blue or white LED lighting at Zeitgeber time 13.5-14 (ZT; ZT0 is the onset of "lights on" and ZT12 is the "lights off" onset under 12-hour light, 12-hour dark schedule). After 33 weeks, only the high irradiance (7.2 J/cm2) of blue LED light reduced the alpha diversity of gut microbiota. The high irradiance of white LED light and the low irradiance (3.6 J/cm2) of both lights did not change microbial alpha diversity. However, the low irradiance, but not the high one, of both blue and white LED illuminations significantly increased serum total cholesterol (TCHO), but not triglyceride (TG). There was no significant difference of microbial abundance between two lights. The ratio of beneficial to harmful bacteria decreased at a low irradiance but increased at a high irradiance of blue light. Notably, this ratio was negatively correlated with serum TCHO but positively correlated with bile acid biosynthesis pathway. Therefore, chronic blue LED lighting at a high irradiance may harvest gut dysbiosis in association with decreased alpha diversity and the ratio of beneficial to harmful bacteria to specifically dysregulates TCHO metabolism in mice. Night shift workers are recommended to be avoid of blue LED lighting for a long and lasting time.

Blue Light Damage and p53: Unravelling the Role of p53 in Oxidative-Stress-Induced Retinal Apoptosis

In the digital age, the widespread presence of electronic devices has exposed humans to an exceptional amount of blue light (BL) emitted from screens, LEDs, and other sources. Studies have shown that prolonged exposure to BL could have harmful effects on the visual system and circadian rhythm regulation. BL is known to induce oxidative stress, leading to DNA damage. Emerging research indicates that BL may also induce cell death pathways that involve the tumor-suppressor protein p53. Activated p53 acts as a transcription factor to regulate the expression of genes involved in cell cycle arrest, DNA repair, and apoptosis. This study aimed to explore the implication of p53 in BL-caused retinal damage, shedding light on the potential mechanisms of oxidative-stress-induced retinal diseases. BL-exposed porcine retinal cultures demonstrated increased p53- and caspase-mediated apoptosis, depending on exposure duration. Direct inhibition of p53 via pifithrin α resulted in the prevention of retinal cell death. These findings raise concerns about the long-term consequences of the current daily BL exposure and its potential involvement in various pathological conditions, including oxidative-stress-based retinal diseases like age-related macular degeneration. In addition, this study paves the way for the development of novel therapeutic approaches for oxidative-stress-based retinal diseases.

The association between time spent on screens and reading with myopia, premyopia and ocular biometric and anthropometric measures in 6- to 7-year-old schoolchildren in Ireland

PURPOSE

More time spent on near tasks has consistently been associated with the promotion of myopia. The World Health Organization advises limiting daily screentime to less than 2 h for children aged five and over. This study explored the relationship between time spent on screens and reading/writing with refractive status, ocular biometric and anthropometric factors in 6- to 7-year-olds in Ireland.

METHODS

Participants were 723 schoolchildren (377 boys [51.8%]), mean age 7.08 (0.45) years. The examination included cycloplegic autorefraction (1% cyclopentolate hydrochloride), ocular biometry (Zeiss IOLMaster), height (cm) and weight (kg). Screentime and reading/writing time were reported by parents/legal guardians by questionnaire. Myopia (≤-0.50D) and premyopia (>-0.50D ≤ 0.75D) risk assessments were performed using logistic regression, and multivariate linear regression was used to analyse continuous variables.

RESULTS

Reported daily screentimes were 31% <1 h, 49.5% 1-2 h, 15.6% 2-4 h and 3.9% >4 h. Reading/writing times were 42.2% frequently, 48.0% infrequently and 9.8% seldom/never. Linear regression, controlling for age and ethnicity, revealed >2 h/day on screens was associated with a more myopic spherical equivalent [β = -1.15 (95% confidence intervals {CIs}: 1.62-0.69, p < 0.001)], increased refractive astigmatism (β = 0.29, CI: 0.06-0.51, p = 0.01), shorter corneal radius (β = 0.12, CI: 0.02-0.22, p = 0.02), higher axial length/corneal radius (β = 0.06, CI: 0.03-0.09, p < 0.001), heavier weight (β = 1.60, CI: 0.76-2.45, p < 0.001) and higher body mass index (BMI) (β = 1.10, CI: 0.28-1.12, p < 0.001). Logistic regression, controlling for age and ethnicity, revealed daily screentime >2 h was associated with myopia (OR = 10.9, CI: 4.4-27.2, p = 0.01) and premyopia (OR = 2.4, CI: 1.5-3.7, p < 0.001). Frequent reading/writing was associated with screentime ≤2 h/day (OR = 3.2, CI: 1.8-5.8, p < 0.001).

CONCLUSION

Increased screentime was associated with a more myopic refraction, higher axial length/corneal radius ratio, increased odds of myopia, premyopia, higher degrees of astigmatism, increased weight, BMI and decreased reading/writing time. Dedicated education programmes promoting decreased screentime in children are vital to prevent myopia and support eye and general health.

Blue light pollution causes retinal damage and degeneration by inducing ferroptosis

With the development of technology and electronic products, the problem of light pollution is becoming more and more serious. Blue light, the most energetic light in visible light, is the main culprit of teenage vision problems in the modern environment. As the tissue with the highest oxygen consumption, the retina is vulnerable to oxidative stress. However, the exact way in which blue light-triggered reactive oxygen species (ROS) cause retinal cell death remains unclear. Ferroptosis is a newly defined cell death pathway, whose core molecular mechanism is cell death caused by excessive lipid peroxidation. In this study, the results indicated that blue light-triggered ROS burst in retinal cells, in the meantime, intracellular Fe²⁺ levels were also significantly up-regulated. Further, deferoxamine (DFO) significantly improved blue light-triggered lipid peroxidation and cell death in ARPE-19 cells, and ferrostatin-1 (Fer-1) alleviated retinal oxidative stress and degeneration in rats. Furthermore, the GSH-GPX4 and FSP1-CoQ₁₀-NADH systems served as key systems for cellular defense against ferroptosis, and interestingly, our results demonstrated that blue light triggered imbalance of the GSH-GPX4 and FSP1-CoQ₁₀-NADH systems in retinal cells. Taken together, these pieces of evidence suggest that ferroptosis may be a crucial pathway for blue light-induced retinal damage and degeneration, which helps us to understand exactly why blue light pollution causes visual impairment in adolescents.

A review of the current state of research on artificial blue light safety as it applies to digital devices

Light is necessary for human health and well-being. As we spend more time indoors, we are being increasingly exposed to artificial light. The development of artificial lighting has allowed us to control the brightness, colour, and timing of our light exposure. Yet, the widespread use of artificial light has raised concerns about the impact of altering our light environment on our health. The widespread adoption of personal digital devices over the past decade has exposed us to yet another source of artificial light. We spend a significant amount of time using digital devices with light-emitting screens, including smartphones and tablets, at close range. The light emitted from these devices, while appearing white, has an emission spectrum with a peak in the blue range. Blue light is often characterised as hazardous as its photon energy is higher than that of other wavelengths of visible light. Under certain conditions, visible blue light can cause harm to the retina and other ocular structures. Blue light can also influence the circadian rhythm and processes mediated by melanopsin-expressing intrinsically photosensitive retinal ganglion cells. While the blue component of sunlight is necessary for various physiological processes, whether the low-illuminance artificial blue light emitted from digital devices presents a risk to our health remains an ongoing area of debate. As technological advancements continue, it is relevant to understand how new devices may influence our well-being. This review examines the existing research on artificial blue light safety and the eye, visual performance, and circadian functions.

Cytotoxicity and genotoxicity of blue LED light and protective effects of AA2G in mammalian cells and associated DNA repair deficient cell lines

Light emitting diode (LED) devices emit narrow bands of the blue, green, and red light spectrum rather than the continuous spectrum emitted from sunlight and fluorescent light bulbs. LED devices have become considerably common in society, and the fluence of blue light from LED devices is more intense than other light sources. Previous studies presented that the blue light spectrum may harness potentially inimical genotoxicity. Therefore, the aim of this study was to investigate this potential cytotoxicity and genotoxicity, as well as identify the mechanism of the cellular effects induced by blue LED light exposure in mammalian cell lines with their DNA repair deficient mutants. Our results demonstrated that blue LED light induced both oxidative stress to cells and cytotoxic and genotoxic effects including reduction of clonogenicity, cell cycle arrest, induction of sister chromatid exchanges, endoreduplicated chromosomes, and increased frequency of HPRT locus mutations. In DNA repair deficient cells, particularly those involving double strand break repair deficiency, cells presented hypersensitivity to blue LED light exposure. Blue LED light also induced chromosome aberrations more in DNA repair deficient cells than wild type cells. The cytotoxicity of blue LED light was reduced by an effective antioxidant, ascorbic acid 2-glucoside, which can suppress blue LED light induced oxidative stress. These results indicated that prolonged, high intensity exposure to blue LED light induces genotoxic stress to cells, and oxidative stress induced by blue LED light is targeting DNA to induce these biological effects.

Indoor Lighting Workplaces

Office work has so far been carried out in company buildings and was largely based on the use of paper on a horizontal surface. Due to multiple reasons, more workers are working in their homes with electronic devices. As a result, both the working environment and personal tools are changing. Since the discovery about 20 years ago of the non-visual ways of light absorption, it was known that apart from the image forming effects (IF) of light from which the criteria for correct lighting have been developed, non-image forming effects (NIF) of light exist. The discovery of NIF has enhanced researcher belief in the importance of daylighting and has raised new criteria to be taken into account for proper interior lighting. Due to all the factors mentioned above, the parameters to be met by a luminaire and its environment for proper lighting of the workstation have been modified and expanded. The rapid advance in the development of new light-emitting diode (LED) luminaires with which the spectral power distribution (SPD) can be practically created opens the door to a genuine technological revolution comparable to the invention of electric lighting around 150 years ago. The authors of this study will review the latest published studies on the importance of light in our lives, IF and NIF effects of light, the parameters which from these effects are suggested to be taken into account for a correct indoor lighting, the regulations in force on indoor lighting workplaces, and proposals to improve indoor lighting and therefore the quality of life of workers.

The Importance of Light in Our Lives

The light that enters through our eyes is not only for vision. The human circadian system responds to light differently than the visual system. The timing of each biological function in mammals is directed by the main clock located in the Supraquiasmic Nucleus, which is regulated by light. However, until now, only the interaction of light with our visual system has been taken into account when choosing the parameters of indoor lighting sources, including those in the classroom. In the publications about school lighting, the first concern was the common parameters of indoor lighting such as horizontal workplane illuminance, illuminance uniformity, and avoiding reflections on different surfaces. In this chapter, the authors show publications about new findings on the effects of light on people, studies carried out in different countries aimed at improving classroom lighting, current regulations on lighting related to classroom lighting, and new parameters that are being considered, along with those already used for new and better lighting.