Research on Blue Light Shows Blue Light Has Harmful Biological Effects

“Insufficient light during the day and excessive light exposure during evening and night hours disrupts the human circadian timing system and may cause impaired sleep, immunity, and mood, and it is associated with increased risks of obesity and diabetes as well as breast, prostate, and other neuroendocrine-sensitive cancers. In 2010, the World Health Organization International Agency for Research on Cancer classified nightshift work with circadian disruption as a probable (group 2A) human carcinogen  and in 2018, the US National Toxicology Program expert panel concluded that circadian disruption caused by excessive light at night and insufficient light during the day is reasonably anticipated to be a human carcinogen. Yet, our modern 24/7 society depends on the use of electric lighting at night and lowered indoor illumination levels during the day. “- Moore Ede et al 2020

5/14/2019 The French Agency for Food, Environmental and Occupational Health & Safety (ANSES) has issued a new report reviewing the scientific evidence on health impacts including vision loss and damaged sleep from the blue light emitted from LED lights and the screens of cell phones, laptops and digital devices. 

“The new scientific data confirm the 2010 result regarding the toxicity of blue light to the eye, which can lead to failing eyesight. They show short-term phototoxic effects associated with acute exposure and long-term effects associated with chronic exposure, which increase the risk of developing age-related macular degeneration.” 

The report states that current ICNIRP optical radiation  limits are non protective in regards to these impacts and cites research linking blue light exposure to damage to the retina of the eye and the disturbance of sleep rhythms. ANSES also highlights that children are an especially vulnerable population as their eyes are still maturing and are unable to filter the blue light out as much as adults. ANSES posits this could lead to an increased risk of age-related macular degeneration (AMD) after chronic exposure to blue light.  AMD is  a leading cause of severe vision loss in adults over age 50. 

The ANSES expert appraisal shows that even very low levels of exposure to blue light in the evening or at night disrupts biological rhythms and therefore sleep. The Agency recommends limiting the use of LED devices with the highest blue-light content, especially for children and pregnant women, and reducing light pollution as much as possible to preserve the environment and protect the public.

Excerpts from the Report include: 

“The Agency confirms the toxicity of blue light on the retina and highlights the biological rhythm and sleep disruption associated with exposure to blue light in the evening or at night, particularly via screens and especially for children.”

“The amount of light received by the retina in the blue band can be large and have phototoxic effects on the eye and a disruptive effect on biological rhythms.”

“Most of the available scientific studies show that blue light alters sleep regulation via circadian disruptions. The evidence provided by studies undertaken in humans is sufficient to conclude that exposure to blue-rich light during the evening has a proven effect on sleep onset latency and the duration and quality of sleep.”

ANSES recommendations to limit the population’s exposure to blue light. 

• • Prefer “warm white” domestic lighting (colour temperature below 3000 K).
  • Limiting the exposure of people – children in particular – to the blue-rich light of LED screens (mobile phones, tablets, computers, etc.) before bedtime and at night.
  • Creating protected spaces, without any artificial lighting.
  • Recommendations for employers to protect workers from the phototoxic effects of blue light by  limiting the exposure of workers to these light sources and informing them of the related hazards. 
  • Recommendations to protect pregnant women: “Given the effects observed on foetal development in animals related to maternal exposure to light at night, the CES recommends limiting the exposure of pregnant women to light during the night.
  • Several susceptible population groups were identified based on research data: infants, children, adolescents and young adults, people with ocular diseases (dry eye, ARMD, glaucoma, retinopathy, etc.); people with motor or cognitive disorders reducing their avoidance or decision-making capacities in the event of overly intense light; people taking photosensitising medications or exposed to photosensitising pollutants, and night workers  and any other professionals with potentially high exposure to LED lighting (surgeons, dentists, lighting professionals, lighting distributors, performing artists, people working in sport facilities, people working in agri-food facilities using LEDs (greenhouses, aquaculture), etc.).
  • Revising the exposure limits for optical radiation proposed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) so  the limits account for chronic exposure and be sufficiently protective against phototoxic risks.
  • Adapting a new regulatory framework for all LED systems 

• Restrict the sale of LED objects to the general public to those in higher risk groups.

• Limit the light intensity of vehicle lights, while guaranteeing road safety.

• Minimise the temporal modulation of the light emitted by all light sources (lighting, screens, other LED objects).

• Establishing standards for protective equipment purporting to protect consumers from blue light such as blue light blocking  lenses, protective eye glasses and  computer screen coverings.

• ANSES stated that the scientific knowledge consistently shows an increase in mortality and a decline in the diversity of the animal and plant species linked to night lighting and LEDs. Regulations to limit light pollution should be strengthened,  while ensuring public safety.

2022 Study: Oriented migratory flight at night: Consequences of nighttime light pollution for monarch butterflies: iScience

• Nighttime light pollution can disturb diurnal migratory monarch butterflies, Exposure to this pollution induces abnormal activity in normally quiescent monarchs, This pollution acts as sensory noise that perturbs the circadian clock of monarchs, Conservation should consider susceptibility of habitat to nighttime light pollution.

“Researchers found that butterflies roosting at night near artificial illumination such as a porch or streetlight can become disoriented the next day because the light interferes with their circadian rhythms. Artificial light can impede the molecular processes responsible for the butterfly’s remarkable navigational ability and trigger the butterfly to take wing when it should be resting.”-Lights can interfere with monarch butterfly’s navigation abilities | University Of Cincinnati

Light at Night

In 2021, the National Toxicology Program  “Review of Shift Work at Night, Light at Night, and Circadian Disruption” concluded there was  “high confidence that persistent night shift work that disrupts circadian rhythms can cause breast cancer in women and may cause prostate cancer in men” and “moderate confidence for a causal relationship between human cancer and certain lighting conditions that cause circadian disruption. Certain lighting conditions are defined as excessive LAN exposure combined with insufficient daylight exposure.”

SCIENCE TO KNOW

Meng Q , Lian Y , Jiang J , et al. Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats. Photochem Photobiol Sci. 2018;17(4):386-394. doi:10.1039/c7pp00271h

• Blue filtered light induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

Heo JY, Kim K, Fava M, et al. Effects of smartphone use with and without blue light at night in healthy adults: A randomized, double-blind, cross-over, placebo-controlled comparison. J Psychiatr Res. 2017;87:61-70. doi:10.1016/j.jpsychires.2016.12.010

• “This study investigated the immediate effects of smartphone blue light LED on humans at night. We investigated changes in serum melatonin levels, cortisol levels, body temperature, and psychiatric measures with a randomized, double-blind, cross-over, placebo-controlled design…”
• “use of blue light smartphones was associated with significantly decreased sleepiness (Cohen’s d = 0.49, Z = 43.50, p = 0.04) and confusion-bewilderment (Cohen’s d = 0.53, Z = 39.00, p = 0.02), and increased commission error “

Nakashima Y, Ohta S, Wolf AM. Blue light-induced oxidative stress in live skin. Free Radic Biol Med. 2017;108:300-310. doi:10.1016/j.freeradbiomed.2017.03.010

• Exposing human skin to the blue light contained in sunlight depressed flavin autofluorescence, demonstrating that the visible component of sunlight has a physiologically significant effect on human skin. The ROS produced by blue light is probably superoxide, but not singlet oxygen. These results suggest that blue light contributes to skin aging similar to UVA.

Janků K, Šmotek M, Fárková E, Kopřivová J. Block the light and sleep well: Evening blue light filtration as a part of cognitive behavioral therapy for insomnia. Chronobiol Int. 2020;37(2):248-259. doi:10.1080/07420528.2019.1692859

• We provide further evidence that blocking short-wavelength light in the evening hours may be beneficial for patients suffering from insomnia.

Circadian Potency Spectrum with Extended Exposure to Polychromatic White LED Light under Workplace Conditions

Nash, T.R., Chow, E.S., Law, A.D. et al. Daily blue-light exposure shortens lifespan and causes brain neurodegeneration in Drosophila. npj Aging Mech Dis 5, 8 (2019).  

• Blue light induces expression of stress-responsive genes in old flies but not in young, suggesting that cumulative light exposure acts as a stressor during aging. We also determined that several known blue-light-sensitive proteins are not acting in pathways mediating detrimental light effects. Our study reveals the unexpected effects of blue light on fly brain and establishes Drosophila as a model in which to investigate long-term effects of blue light at the cellular and organismal level.

Light at Night

Dong Zhang, Rena R Jones, Peter James, Cari M Kitahara, Qian Xiao. Associations between artificial light at night and risk for thyroid cancer: A large US cohort study. Cancer. 2021 Feb 8. doi: 10.1002/cncr.33392. 

• Among 464,371 participants, a positive association was found between LAN and thyroid cancer risk… In women, the association was stronger for localized cancer, whereas in men, the association was stronger for a more advanced stage. Results were consistent across different tumor sizes.

Ariadna Garcia-Saenz et al, Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study), Environmental Health Perspectives (2018). DOI: 10.1289/EHP1837

• The study was conducted within the framework of the MCC-Spain project, and includes medical and epidemiological data of more than 4,000 people between 20 and 85 years of age in 11 Spanish regions. Indoor exposure to artificial light was determined through personal questionnaires, while outdoor levels of artificial light were evaluated for Madrid and Barcelona, based on nocturnal images taken by astronauts aboard the International Space Station.
• Results obtained for both cities show that participants exposed to higher levels of blue light had a 1.5 and two-fold higher risk of developing breast and prostate cancer, respectively, as compared to the less-exposed population.

Garcia-Saenz, Ariadnaa–c; de Miguel, Alejandro Sánchezd–g; Espinosa, Anaa–c,h; Costas, Laurab,i; Aragonés, Nuriab,k; Tonne, Cathryna–c; Moreno, Victorb,i,j,l; Pérez-Gómez, Beatrizb,m; Valentin, Antoniaa,c,h; Pollán, Marinab,m; Castaño-Vinyals, Gemmaa–c,h; Aubé, Martinf; Kogevinas, Manolisa–c,h Association Between Outdoor Light-at-night Exposure and Colorectal Cancer in Spain, Epidemiology: September 2020 – Volume 31 – Issue 5 – p 718-727

• We investigated the association between exposure to ALAN according to light spectrum and colorectal cancer among subjects who had never worked at night in a general population case–control study in Spain.
• Exposure to blue light spectrum was positively associated with colorectal cancer (OR = 1.6; 95% CI: 1.2–2.2; highest vs. lowest tertile).
• Outdoor blue light spectrum exposure that is increasingly prevalent in recent years may be associated with colorectal cancer risk.
• See video abstract: http://links.lww.com/EDE/B708.

Höhn C, Schmid SR, Plamberger CP, Bothe K, Angerer M, Gruber G, Pletzer B, Hoedlmoser K. Preliminary Results: The Impact of Smartphone Use and Short-Wavelength Light during the Evening on Circadian Rhythm, Sleep and Alertness. Clocks & Sleep. 2021; 3(1):66-86. https://doi.org/10.3390/clockssleep3010005

• “There is growing evidence that short-wavelength light affects hormonal secretion, thermoregulation, sleep and alertness. ..Cortisol was elevated in the morning after reading on the smartphone without a filter, which resulted in a reduced cortisol awakening response. Evening melatonin and nightly vasodilation (i.e., distal-proximal skin temperature gradient) were increased after reading on printed material. Early slow wave sleep/activity and objective alertness in the morning were only reduced after reading without a filter. These results indicate that short-wavelength light affects not only circadian rhythm and evening sleepiness but causes further effects on sleep physiology and alertness in the morning. Using a blue light filter in the evening partially reduces these negative effects.”

Effects and mechanisms of action of light-emitting diodes on the human retina and internal clock.