Olli Posti, a pioneer in the natural wellness industry, author and inspiring wellness influencer, has become known for inspiring people to make better choices in both their diet and lifestyle. His passion for natural and healthy lifestyles has influenced the everyday lives of many. Olli has put together an expert and comprehensive summary for North Ray on blue light – a topic that has become increasingly important in terms of sleep quality, eye health and overall well-being.
The effect of light on sleep
Internal clock - blue light sets the human rhythm
https://pubmed.ncbi.nlm.nih.gov/31433569 (from 2019)
“Visible light synchronizes the human biological clock in the hypothalamic nuclei to the solar circadian cycle. Short wavelengths, perceived as blue light, are the strongest synchronizing agent for the circadian system, which keeps most biological and psychological rhythms internally synchronized. Circadian rhythm is important for optimal functioning of organisms, and disruptions or chronic imbalances in the circadian sleep-wake rhythm can often lead to psychiatric and neurodegenerative diseases. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends not only on the spectral composition of the light, but also on the timing of light exposure and its intensity.
While exposure to blue light is important for maintaining well-being, alertness, and cognitive performance during the day, chronic exposure to low-intensity blue light just before bedtime can have serious effects on sleep quality, circadian phase, and cycle duration. This inevitably highlights the need to find solutions to improve well-being, alertness, and cognitive performance in today's society, where exposure to blue light-emitting devices is constantly increasing.”
“Blue light is currently considered to have the strongest effect on the synchronization of the human circadian rhythm. Exposure to even a small amount of blue light or otherwise bright light at night or before bedtime can disrupt circadian rhythms, with serious general health effects. At the same time, exposure to blue light during the day is vital for the vitality of organisms.”
“A simple solution that can effectively block and reduce the blue part of the light spectrum before bedtime is blue-light blocking glasses and lenses. Wearing blue-light blocking glasses before bedtime can effectively reduce melatonin suppression caused by LED light, thereby potentially facilitating adaptation to new social schedules and reducing sleep disorders and their consequences among the population. Reducing the blue part of artificial light at night could protect shift workers from consequences such as cancer and cardiovascular diseases. It is important that any solution takes into account the optimal spectral requirements of both conscious and unconscious light perception.”
Light exposure behavior predicts mood, memory, and sleep quality
https://www.nature.com/articles/s41598-023-39636-y (2023)
“Increased cell phone use before bed predicted delayed circadian rhythm, poorer sleep quality, and increased memory and concentration difficulties.”
Nighttime blue light blocking against insomnia: A randomized controlled trial
“Using electronic devices that emit light before bed can contribute to or worsen sleep problems.
Exposure to blue light, especially from these devices, can affect sleep by suppressing melatonin and causing neurophysiological arousal. Our aim was to determine whether wearing orange-yellow blue light blocking lenses before bed would improve sleep in individuals with insomnia.”
“Yellow-orange lenses are a safe, affordable, and easy-to-implement treatment for insomnia symptoms.”
Artificial light at night: a neglected public health problem in the built environment
“Research on the links between the built environment and population health has largely focused on physical activity and social connections, the associated health risks or benefits and the chronic diseases they cause, as well as access to healthy food, exposure to green spaces or green spaces, noise abatement, air pollution and biodiversity. Artificial night-time light is mentioned as a sleep disruptor, but it does not seem to be a future challenge for urban planning and health; indeed, one “healthy by design” brochure considers light only as a pedestrian amenity and bright light as ecological and astronomical pollution.
This commentary draws the attention of the public health community to the health risks of artificial light at night from streetlights, illuminated signs, and illuminated buildings. Artificial light at night has increased exponentially since public lighting was introduced about 130 years ago, and more than half of the world’s population now lives under night skies brighter than a full moon. Artificial light at night is a growing and significant concern for human health because it disrupts melatonin production; changes in melatonin alter the body’s circadian rhythm (synchronization), leading to increased risk of cancer, sleep disorders, and cognitive problems. The American Medical Association has suggested that other diseases that may be exacerbated by circadian disruption caused by artificial light at night include obesity, diabetes, depression, and reproductive disorders.
“Education and action on this phenomenon is particularly urgent in Australia, as many municipalities are currently reviewing their street lighting, and their focus has been on energy conservation rather than human health, as Australian local governments spend up to 50% of their energy budget on street lighting. Both local governments and citizens need to be informed about the links between nighttime light and health, and it is important to consider how the spectrum (colour/wavelength) of light exposure affects human health.”
The effect of reducing blue light from smartphone screens on students' subjective sleep quality
https://www.tandfonline.com/doi/abs/10.1080/07420528.2023.2173606 (2022)
“Human exposure to artificial light at night, where the blue part of the visible spectrum is dominant, strongly affects circadian rhythms and sleep via melanopsin-containing retinal ganglion cells.”
“The study showed that reducing blue light emissions from mobile phone LED screens at night improves students' subjective sleep quality, daytime functioning, and bedtime.”
Blocking blue light during mania - sleep regularity increases significantly and symptoms improve quickly
https://onlinelibrary.wiley.com/doi/abs/10.1111/bdi.12265 (2014)
“Pharmacological treatment of mania is inadequate. Virtual darkness therapy (blue light blocking with orange-tinted glasses) is a promising new treatment option for mania. It may be based on the recently identified blue light-sensitive retinal photoreceptor, which is solely responsible for photostimulation of the circadian master clock. This is the first case report describing the clinical course of a closely monitored, hospitalized patient with a manic episode who received clear lenses first and then blue light blocking glasses.”
“Manic symptoms remained unchanged during the first seven days. When switching to blue light blocking, manic symptoms decreased rapidly and permanently, in addition to a decrease in total sleep, decreased motor activity during sleep episodes, and a significant increase in sleep regularity. The patient’s total length of hospital stay was 20 days shorter than the average during his previous manic episodes.
Conclusions
The unusually rapid reduction in symptoms, accompanied by consistent changes in sleep parameters towards markedly increased regularity, suggests that antispasmodics may target a key mechanism in the pathophysiology of mania.”
Changes in blood pressure and sleep duration in patients with blue light blocking/yellow tinted intraocular lenses
https://www.nature.com/articles/hr201450 (2014)
“Systolic and diastolic blood pressure decreased significantly in the entire patient group after implantation. Systolic blood pressure decreased significantly more 1 month after implantation in patients who received a yellow-tinted intraocular lens than in patients who received an ultraviolet (UV)-filtering lens. Post-implantation sleep duration, including daytime naps, was reduced in patients who had overslept and increased in patients who had underslept prior to lens implantation. Our findings suggest that a yellow-tinted lens is better for patients with high blood pressure than a UV-filtering lens.”
Implantation of a blue-light-blocking intraocular lens improves sleep quality in cataract patients
https://jcsm.aasm.org/doi/full/10.5664/jcsm.2908 (2013)
“Blue light blocking lenses had a significantly beneficial effect on sleep quality in cataract patients.”
Effects of pre-bedtime blue light exposure on the ratio of deep sleep to deep sleep in healthy young men.
https://www.sciencedirect.com/science/article/abs/pii/S1389945721003257 (2021)
“These results suggest that exposure to blue light affects sleep quality by reducing the proportion of deep sleep.”
Blue light from digital devices - impact on sleep
https://apcz.umk.pl/JEHS/article/view/44026 (2023)
“The blue light from various digital devices affects sleep by shortening and worsening sleep quality, making it harder to fall asleep, worsening the feeling of sleep deprivation, and increasing feelings of fatigue.”
“As sleep disorders and new habits increase in society, researchers note that it is necessary to monitor the perceived effects of blue light on sleep.”
Strategies to reduce social jet lag: Reducing blue light in the evening promotes sleep and melatonin.
https://onlinelibrary.wiley.com/doi/abs/10.1111/ejn.14293 (2018)
“Controlling light exposure at home may be effective in promoting melatonin secretion and sleep, helping late chronotypes better cope with early social schedules.”
Turn off the lights and sleep well: Filtering blue light in the evening as part of cognitive behavioral therapy for insomnia.
https://www.tandfonline.com/doi/abs/10.1080/07420528.2019.1692859 (2019)
Detection of sleep disturbances caused by the use of blue light-emitting devices at bedtime and their impact on the habits and sleep quality of young medical students
https://onlinelibrary.wiley.com/doi/full/10.1155/2019/7012350 (2019)
“The use of devices that emit blue light (smartphones, tablets, and laptops) at bedtime has negative effects on sleep due to photostimulation and/or problematic overuse.”
Interventions to reduce shortwave (or “blue”) light exposure at night and their effects on sleep: A systematic review and meta-analysis
https://academic.oup.com/sleepadvances/article/1/1/zpaa002/5851240 (2020)
“Light affects sleep-wake and circadian rhythms, especially in the short-wavelength part of the visible spectrum. Most personal electronic devices that emit light contain high levels of this so-called “blue” light. Exposure to these devices in the evening can disrupt sleep. Measures to reduce exposure to short-wavelength light before bedtime can reduce the adverse effects on sleep.”
Exposure to light in the evening disrupts a person's sleep, biological rhythms, and attention span.
“In recent years, exposure to bright light has exploded in much of the world, as electronic screens emit bright light directly into the eyes. Millions of computers, tablets, televisions and smartphones are purchased worldwide every month, and the usage time of these devices is increasing all the time. Most of these devices are equipped with LED (Light Emitting Diode) screens, which expose users to continuous short-wavelength (blue) light.”
Blocking the short-wavelength component of visible light emitted by smartphone screens improves human sleep quality
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6280115 (2018)
“It has been shown that the short-wavelength blue component of the visible light spectrum can alter circadian rhythms and reduce the levels of the hormone melatonin. The short-wavelength light emitted by smartphone screens may affect the sleep quality of people who use these devices at night by minimizing the levels of melatonin.”
“The results obtained in this study support the hypothesis that blue light may inhibit melatonin secretion more than longer wavelengths of the visible light spectrum. In this study, the use of a yellow-orange filter significantly improved sleep quality. Overall, these findings lead to the conclusion that blocking the short-wavelength component of light from smartphone screens improves human sleep.”
The effect of light on the skin
The effect of blue light and digital screens on the skin
https://onlinelibrary.wiley.com/doi/full/10.1111/jocd.15576 (2023)
“The skin is inevitably exposed to blue light due to the increased use of indoor lighting, smartphones and laptops, and they have many harmful effects.”
“Numerous studies have shown that exposure to blue light accelerates the aging process and causes skin hyperpigmentation. It also alters circadian rhythms. The two main molecules that mediate cellular responses to blue light are nitric oxide (NO) and reactive oxygen species. However, the exact process is still not fully understood.
Conclusion
These negative consequences can ultimately lead to more general skin damage that can accelerate the aging process. Sometimes, protecting your skin can be crucial in protecting against blue light.
About blue and artificial light in general
Blue light: Blessing or curse?
https://www.sciencedirect.com/science/article/pii/S2351978915004606 (2015)
“Good lighting design in the workplace requires multidisciplinary knowledge and participation. This goes beyond economic issues. Today, we are forced to reduce energy consumption, which can be achieved by using LED lighting. When architects/designers create or modify a workplace, they must keep in mind the simple fact that they are not designing for themselves, according to their own aesthetic values, culture and preferences. The environment evokes different emotions, and light can and should be used to evoke the best emotions and avoid the worst ones. It seems that we spend almost 90 percent of our lives in some kind of indoor environment. However, visible light extends from 360 nm to 780 nm, which affects us in different ways. Light affects our body and mind both visually and non-visually, and they are essential for our biological needs to remain in balance. These non-visual functions depend on the intraretinal photosensitive ganglion cells (ipRGCs). The main concern of lighting design is to provide good light for vision, but non-visual functions are those that regulate and synchronize our biological functions, such as circadian rhythms, pupillary light reflex, melatonin regulation, cognitive performance, mood, locomotor activity, memory, body temperature, etc. It should be borne in mind that, for example, blue light is present in natural light, but also in artificial light. Today, there are many light sources containing blue light, especially in technical devices. Blue light is essential because it triggers physiological reactions and is important for visual processes such as color perception, despite studies that show the opposite. Memory, alertness, attention, reaction times, learning ability and cognitive performance are enhanced by blue light, but it can also inhibit melatonin secretion.”
Effects of blue light on the eye: A systematic literature review
https://www.theseus.fi/handle/10024/99301 (2015)
“High levels of blue light are harmful to the retina, particularly causing cell death. Long-term exposure to radiation also causes similar changes in tissues.”
Blue Light Exposure: A Narrative Review: Eye Risks and Prevention
https://link.springer.com/article/10.1007/s40123-023-00675-3 (2023)
“Exposure to blue light has increased significantly in our environment since the widespread use of light-emitting diodes (LEDs) and digital devices that emit a lot of blue light. This raises questions about its potential adverse effects on eye health. The aim of this review is to provide up-to-date information on the ocular effects of blue light and to discuss the effectiveness of prevention and protection methods for blue light-induced eye damage.”
Violet light exposure may be a preventive strategy against myopia progression
https://pubmed.ncbi.nlm.nih.gov/28063778 (2017)
“The prevalence of myopia is increasing worldwide. Outdoor exposure is one of the most important environmental factors for myopia management. In this study, we demonstrate that violet light (wavelength 360-400 nm) suppresses myopia progression. First, we confirmed that violet light suppressed axial length elongation in a chick myopia model. The function of the myopia suppressor gene EGR1 was enhanced by violet light exposure. Violet light exposure induced a significantly greater upregulation of EGR1 in chick chorioretinal tissues than blue light under the same conditions. Next, we conducted a clinical study to retrospectively compare AL elongation among myopic children wearing glasses (violet light-blocking) and two types of contact lenses (partially violet light-blocking and violet-transmitting). The data showed that violet-transmitting contact lenses suppressed myopia progression the most. These results suggest that violet light is one of the important outdoor environmental factors in the management of myopia. Since violet light exposure is excluded from modern society due to excessive UV protection, violet light exposure may be a preventive strategy against the progression of myopia.”
The Dangers of Blue Light: A True Story!
https://pubmed.ncbi.nlm.nih.gov/27039979 (2016)
“There have been numerous publications on the dangers of blue light, both for the scientific community and the general public. The new and abundant development of light sources emitting potentially toxic blue light (415-455 nm) extends from LED lamps (Light Emitting Diodes) for indoor lighting to television screens, computers, digital tablets and smartphones using OLED (Organic Light Emitting Diode) or AMOLED (Active-Matrix Organic Light Emitting Diode) technology.”
“LED lamps, whether used as components for indoor lighting or displays, are of concern if used for long periods of time and at short distances.”
“It is more difficult to protect against LED bulbs used in indoor lighting, the use of which should be limited to white warm bulbs (2700K). For OLED or AMOLED displays, the only effective way to protect against them is to use them occasionally and only for short periods of time.”
Bigger, Brighter, Bluer, Better? Current Light-Emitting Devices - Harmful Sleep Properties and Preventive Strategies
https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2015.00233/full (2015)
“All light-emitting devices tested were bright and characterized by abundant emissions of short wavelengths. Since this type of light is likely to cause the most sleep disturbances, as it is the most effective at suppressing melatonin and increasing alertness, it must be recognized that at night, ‘brighter’ is not synonymous with ‘better’. Ideally, future software design could be better optimized when nighttime use is anticipated, and the hardware should enable an automatic ‘sleep mode’ in which blue and green light emissions change to yellow and red and the light intensity is reduced.”
Using custom glasses and blue-light-blocking lamps at night may prevent postpartum depression
“In 2001, it was discovered that exposing the eyes to visible blue light inhibits the production of the sleep hormone melatonin. New mothers have to get up at night to care for their babies. This is the time when melatonin normally flows. Exposing their eyes to light can interrupt that flow. It can also reset their circadian clock. On subsequent nights, melatonin may not start flowing at the normal time, making it difficult to fall asleep. Over time, melatonin disruption and sleep deprivation can lead to depression.”
“The risk of postpartum depression may be reduced when a new mother avoids exposing her eyes to blue light when she gets up at night to care for her baby. In the meantime, all new mothers can benefit from using blue light-blocking glasses and lamps when they get up at night to care for their baby.”
The spectrum of melatonin regulation in humans: Evidence for a novel circadian photoreceptor
https://cdn.shopify.com/s/files/1/1014/4865/files/6405.full.pdf (2001)
“The 446-477 nm portion of the spectrum is the most effective wavelength to provide circadian input for the regulation of melatonin secretion. These data suggest that the primary melatonin suppression system is distinct from the visual rod and cone photoreceptors. Finally, this spectrum of action suggests the existence of a novel retinaldehyde photopigment that mediates human circadian photoelectric sensing. These findings open the possibility of optimizing the use of light for both therapeutic and architectural applications.”
Recommendations for indoor exposure to daytime, evening, and nighttime light to support physiology, sleep, and wakefulness in healthy adults
https://cdn.shopify.com/s/files/1/1014/4865/files/journal.pbio.3001571.pdf (2022)
Blue light causes mitochondrial DNA damage and free radical production in epithelial cells.
Possible biological and ecological effects of flashing artificial light
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4038456 (2014)
“Organisms have evolved in the presence of stable natural light systems, and have used them to control key ecological processes. However, the extent and density of artificial lighting in our environment have recently increased, causing large-scale changes to these systems. Indeed, night-time electric lighting is known to significantly disrupt phenology, behavior, and reproductive success, and thus community composition and ecosystem functioning. To date, most attention has focused on the effects of the occurrence, timing, and spectral composition of artificial lighting. Little consideration has been given to the fact that many types of lamps do not produce a continuous stream of light but rather a series of pulses. This flickering light has been shown to have adverse effects on humans and other species.”
“Flashing artificial light has significant potential to produce ecological impacts that have not been previously considered.”
The effect of fluorescent lighting flicker on well-being, performance and physiological arousal
https://pubmed.ncbi.nlm.nih.gov/9557586 (from 1998)
“In workplaces around the world, fluorescent tubes are the dominant light source. Yet very little research has been done on the impact of invisible flicker from fluorescent tubes.”
Flicker in LED lighting, its impact on health and the need to reduce flicker
“Current light-emitting diode (LED) lighting technologies sometimes produce flicker at frequencies that can have adverse health effects. Although it is not always obvious to the human eye, flicker can have an impact under certain conditions.
Many LED lights available on the market flicker at a much higher rate than traditional lights. This flicker can have a negative impact on health. The various adverse effects of flicker include eye strain, fatigue, headaches, migraines, blurred vision, and photoepileptic seizures in susceptible individuals.”
Retinal damage caused by commercial light-emitting diodes (LEDs)
https://www.sciencedirect.com/science/article/abs/pii/S0891584915001586 (2015)
“The spectra of ‘white LEDs’ are characterized by a strong emission in the blue region of the visible spectrum, which is not found in the spectra of daylight. This blue component and strong emission are the main concerns about the health risks of LEDs related to their harmfulness to the eyes and retina. The aim of our study was to investigate the role of blue light from LEDs in retinal damage.”
“LED light induced a retinal distress state with oxidative damage and retinal damage. We observed photoreceptor loss and activation of caspase-independent apoptosis, necroptosis, and necrosis. The effects were found to be wavelength-dependent. The phototoxicity of LEDs on the retina is characterized by severe photoreceptor damage and induction of necrosis.”
Progress in research on the effects of blue light on the eyes and its prevention
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288536 (2018)
“In recent years, people have paid more and more attention to the effects of light pollution on their eyes. The short-wave blue light in the visible spectrum, with a wavelength of 415-455 nm, is closely related to light damage to the eyes. This high-energy blue light passes through the cornea and lens to the retina, causing diseases such as dry eye, cataracts, age-related macular degeneration, and even stimulates the brain, inhibits melatonin secretion, and increases adrenal cortex hormone production, which destroys hormonal balance and directly affects sleep quality. Therefore, the effects of blue rays on the eyes are becoming an important concern in the future.”
Evening glasses
Blue-blocking glasses block the ability of bright light to suppress melatonin production
“It was recently discovered that the biological clock is most sensitive to short wavelengths (blue light). Therefore, we tested the hypothesis that cutting the blue part of the light spectrum with orange lenses would prevent light-induced melatonin suppression.”
“Blue light blocking glasses are an elegant way to prevent light-induced melatonin suppression.”
Protective effect of blue light blocking glasses for adults against light pollution caused by self-illuminating devices used at night
“We studied sleep quality and melatonin in 12 adults who wore blue light blocking glasses or control glasses 2 hours before bedtime while using a self-illuminating portable device, and assessed visual quality with both types of glasses. Nighttime melatonin secretion was significantly higher with blue light blocking than with control glasses. Sleep efficiency and sleep latency were significantly better in blue light blocking users, and this group reported greater sleepiness during portable device use compared to control glasses. Participants rated the blue light blocking as providing acceptable visual quality for screen viewing.”
Blue light blocking glasses as a countermeasure to the alarming effects of evening LED screen exposure in male adolescents
https://www.sciencedirect.com/science/article/abs/pii/S1054139X14003243 (2015)
“Blue light blocking glasses may be useful for young people as a countermeasure to the effects of light exposure from LED screens, and thus potentially prevent the negative effects of modern lighting on circadian physiology in the evening.”
Yellow-orange lenses that block blue light and improve sleep: a randomized study
https://pubmed.ncbi.nlm.nih.gov/20030543 (2009)
“Not all light is created equal: blue wavelengths are the most effective part of the visible electromagnetic spectrum in regulating circadian rhythms. Therefore, blocking blue light could create a form of physiological darkness. Because the timing and amount of both light and darkness affect sleep, wearing blue-light blocking lenses in the evening may affect sleep quality. Light and sleep affect mood, so blocking blue light may affect mood. In this study, 20 adult volunteers were randomized to wear either blue-light blocking (orange-yellow) or yellow-tinted (blocking only ultraviolet light) sunglasses for 3 hours before bed.”
“At the end of the study, the blue-light blocking lens group had significantly improved sleep quality compared to the control group. Mood also improved significantly compared to the control group.”
Blue-blocking glasses worn at night for improving sleep and mood disorders: a systematic review
https://www.tandfonline.com/doi/abs/10.1080/07420528.2021.1930029 (2021)
“Blue light blocking glasses improve sleep by inducing the onset of melatonin at dusk by reducing the activation of retinal ganglion cells that are most sensitive to blue light, which are a major factor in circadian regulation.”
“A systematic search of the scientific literature identified a total of 29 experimental publications using blue-blocking glasses in the evening for the treatment of sleep or mood disorders. These consisted of 16 randomized controlled trials published in journals with a total of 453 patients, 5 uncontrolled trials, 1 case series, 1 case study, and 6 abstracts from conference proceedings. Only 1 case study and 1 RCT involved acutely manic patients, but both showed a significant reduction in manic symptoms with the use of blue-blocking glasses; these provide preliminary clinical evidence of efficacy, making blue-blocking glasses a very promising intervention for the study of bipolar disorder.”
“There was significant evidence from 24 sleep-focused publications that blue-blocking glasses are a successful intervention for reducing sleep onset latency in patients with sleep disorders, jet lag, or shift work. Given the established biological mechanism and clinical studies showing that blue-blocking glasses are effective in inducing sleep, they can be recommended for patients with insomnia or delayed sleep phase.”
Using special glasses or lamps that block blue light at night may reduce cancer risk
https://pubmed.ncbi.nlm.nih.gov/19375243 (2009)
“For over 15 years, there has been accumulating evidence that there is a link between melatonin deficiency and cancer, particularly breast, ovarian and prostate cancer. For the same period, it has been known that exposing the eyes to light when melatonin is normally flowing reduces or completely eliminates melatonin flow. What is relatively new is that melatonin loss is primarily due to blue wavelengths. Blocking these blue rays with orange-yellow glasses restores melatonin flow.”
“This leads to the hypothesis that wearing yellow glasses (or using blue-free lamps) for a few hours before bedtime maximizes melatonin production and reduces the risk of breast, ovarian, and prostate cancer, and possibly other cancers.”
Suppressing blue light at night improves metabolic disorders by regulating circadian rhythms
https://pubmed.ncbi.nlm.nih.gov/31504080 (2019)
“In a clinical study, after wearing blue light blocking glasses for one month, fasting plasma glucose levels, insulin resistance, and sleep quality improved.
Conclusions: Our results suggest that blocking blue light at night is effective in maintaining circadian rhythms and metabolism.”
Books
Light: Medicine of the Future: How We Can Use It to Heal Ourselves NOW
https://www.amazon.com/Light-Medicine-Future-Heal-Ourselves/dp/1879181010
Jacob Liberman, year 1990
Take Off Your Glasses and See: A Mind/Body Approach to Expanding Your Eyesight and Insight
https://www.amazon.com/Take-Off-Your-Glasses-See/dp/0517886049
Jacob Liberman, 1995
The Body Electric: Electromagnetism And The Foundation Of Life
https://www.amazon.com/Body-Electric-Electromagnetism-Foundation-Life/dp/0688069711
Robert Becker, 1998
The Healing Sun: Sunlight and Health in the 21st Century
https://www.amazon.com/Healing-Sun-Sunlight-Health-Century/dp/1899171975
Richard Hobday, 2000
Health and Light: The extraordinary Study that Shows How light Affects Your Health and emotional well being
https://www.amazon.com/Health-Light-extraordinary-Affects-emotional/dp/0898040981
John Ott, 2000
Going Somewhere: Truth about a Life in Science
https://www.amazon.com/Going-Somewhere-Truth-about-Science/dp/0981854915
Andrew Marino, 2011
Light in shaping life: Biophotons in Biology and medicine
https://www.amazon.com/Light-shaping-life-Biophotons-medicine/dp/9081884328
Roeland van Wijk, from 2014
Luminous Life: How the Science of Light Unlocks the Art of Living
https://www.amazon.com/Luminous-Life-Science-Unlocks-Living/dp/1608685179
Jacob Liberman, 2011
Change media
New research sheds light on the functioning of the circadian rhythm (2023)
https://phys.org/news/2023-04-circadian-rhythms.html
“In flies and other insects, cryptochromes activated by blue light serve as the primary photosensors that regulate circadian rhythms. The target of the cryptochrome photosensor, known as ‘Timeless’ (TIM), is a large and complex protein that has not previously been imaged, so its interaction with cryptochrome is not well understood.
Circadian rhythms basically operate through genetic feedback loops. The researchers found that the TIM protein and its partner, the Period (PER) protein, work together to suppress genes that are responsible for their own production. When there is an appropriate delay between the events of gene expression and repression, an oscillation in protein levels occurs.
This oscillation represents "the ticking of a clock, and it appears to be quite unique in circadian rhythms," says senior author Brian Crane.
According to Crane, blue light changes the chemistry and structure of the flavin cofactor of cryptochrome, allowing the protein to bind to the TIM protein and block TIM's ability to repress gene expression and thereby reset the oscillation.”
Are blue light blocking glasses effective? (2023)
https://www.uhhospitals.org/blog/articles/2023/08/are-blue-light-blocking-glasses-effective
“Because blue light from digital screens can disrupt melatonin, it is recommended to stop using digital devices at least two hours before bedtime. However, most people do not follow this advice.
Blue light blocking glasses may be helpful in these circumstances. “One study found that when blue light blocking glasses were worn two hours before bedtime, they improved sleep and performance at work the next day,” says Dr. Stokkermans.”
Blue Light Has a Dark Side (2024)
https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side
“While any type of light can suppress melatonin secretion, blue light at night does so more strongly. Harvard researchers and colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light and green light of similar brightness. Blue light suppressed melatonin for about twice as long as green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).
In another study on blue light, researchers at the University of Toronto compared melatonin levels in people exposed to bright indoor light while wearing blue-light-blocking glasses with those exposed to regular dim light without the glasses. The fact that hormone levels were about the same in the two groups supports the hypothesis that blue light strongly suppresses melatonin. It also suggests that shift workers and night owls might be able to protect themselves by wearing blue-light-blocking glasses. Cheap sunglasses with orange-tinted lenses block blue light, but they also block other colors, making them unsuitable for indoor use at night. Glasses that block only blue light can cost up to $80.
Exposure to blue LED light
If blue light has adverse health effects, environmental concerns and the drive for energy-efficient lighting may conflict with personal health. Compact fluorescent lamps and LEDs are much more energy-efficient than the old-fashioned incandescent bulbs we grew up with. But they also tend to produce more blue light.
The physics of fluorescent bulbs cannot be changed, but the coatings inside the bulbs can be changed to produce a warmer, less blue light. LED lights are more energy efficient than fluorescent bulbs, but they also produce quite a bit of light in the blue spectrum.
Protect yourself from nighttime blue light exposure
- Opt for dim red for night lights. Red light is gentler on melatonin and circadian rhythms.
- Avoid looking at bright screens two to three hours before bedtime.
- If you work the night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters out blue and even green wavelengths at night.
- Get plenty of exposure to bright light during the day, which will improve your sleep at night and your mood and alertness during the day.”
The connection between blue light and sleep? (2020)
https://www.healthline.com/nutrition/block-blue-light-to-sleep-better
“Blue light disrupts sleep
Your body has an internal clock that regulates your circadian rhythm, or 24-hour biological cycle, which affects many internal functions.
It determines when your body is ready to be awake or sleep.
The circadian rhythm needs signals from the external environment – primarily daylight and darkness – to regulate itself.
Blue wavelength light stimulates sensors in your eyes to send signals to your brain's internal clock.
Getting blue light, especially from the sun, during the day helps you stay alert while improving performance and mood.
Modern light bulbs and electronic devices, especially computer screens, produce large amounts of blue light, and they can disrupt your internal clock if you are exposed to them in the evening.
When it gets dark, the pineal gland secretes the hormone melatonin, which tells the body to get tired and go to sleep.
Blue light, whether from the sun or a laptop, effectively suppresses melatonin production, thereby reducing both the quantity and quality of sleep.
Studies link melatonin suppression in the evening to various health problems, including metabolic syndrome, obesity, cancer, and depression.
Feeling blue about the evidence for blue-blocking glasses (2023)
“The Cochrane review mixed studies that used orange blue-light blocking glasses with studies that used clear lenses that don’t block blue light well – and other studies that didn’t bother to specify the type or brand of blue-light blocking glasses tested. Quite a mess.”
Do blue light blocking glasses help you sleep better? (2013)
Exposure to artificial light at night disrupts sleep.
https://www.psychologytoday.com/intl/blog/sleep-newzzz/201309/blocking-blue-light-helps-sleep
“Research in recent years has shown that blue wavelengths are particularly detrimental to circadian rhythm function. Studies have shown that blue wavelength light has uniquely detrimental effects on humans and suppresses melatonin levels more strongly than other wavelengths of light. Unfortunately, many energy-efficient light sources produce high concentrations of blue light. Blue light is emitted by electronic devices, energy-efficient light bulbs, and other [now] common light sources.
Studies investigating blue light blocking — most often in the form of protective glasses that filter out this wavelength of light — have shown promise. A new study in cataract patients suggests that artificial lens implants can improve sleep. Researchers at Sichuan University in China studied the effects of blue light-blocking artificial lenses implanted during cataract surgery. The study involved 40 patients who underwent cataract surgery in both eyes. Cataract surgery usually involves removing the damaged lens in the eye and inserting artificial lenses. Cataracts are a common condition in older adults — about 60 percent of people over the age of 60 have cataracts. The study participants — 26 women and 14 men, with an average age of 74 — were given artificial lenses that block blue light. The researchers assessed the patients’ sleep quality before surgery and again two months after surgery. They found that patients' sleep had significantly improved across several different metrics:
- Patients slept more during the night
- Sleep quality had improved
- The number of daytime disturbances due to sleepiness had decreased.
- The number of patients who met the criteria for “poor sleepers” had decreased.
What is contained in color? The unique effects of blue light on humans (2010)
https://cdn.shopify.com/s/files/1/1014/4865/files/ehp-118-a22.pdf
“In 1958, J. Woodland Hastings and Beatrice M. Sweeney tested the effect of different wavelengths of light—corresponding to different colors—on the circadian rhythm of a photosynthetic marine dinoflagellate. Blue had the greatest power to reset the organism’s circadian clock.
Hastings and Sweeney's paper, published in the December 1958 issue of the Biological Bulletin, gathered dust for decades. No one thought that these findings could have any relevance to humans, whose circadian rhythms were then widely believed to be relatively ignorant of light. However, scientific discoveries over the past two decades have changed all that. Not only does light reset our circadian rhythms, but the same blue light that most strongly affects the activity of dinoflagellates has an equally powerful effect on resetting our own clocks. While most visible wavelengths can reset our clocks, blue light does the job most effectively.
Now, researchers are increasingly recognizing that an irregular circadian rhythm is a health risk. 'Maintaining a synchronized circadian rhythm is important for health and well-being,' says Dieter Kunz, head of the Sleep Research and Clinical Chronobiology Research Group at the Charité-Universitätsmedizin in Berlin. 'Increasing evidence suggests that circadian rhythm desynchronization may play a role in various tumor diseases, diabetes, obesity and depression.'
Shift workers, which Kunz calls a “pattern of internal desynchronization,” are known to suffer from and die at higher rates from a variety of diseases, including cardiovascular disease and cancer. In fact, the World Health Organization determined in 2007 that shift work is a risk factor for breast cancer, and based on this, the Danish government began paying compensation to some female shift workers who develop breast cancer in 2009.”
Computer vision syndrome
https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/computer-vision-syndrome
“Computer vision syndrome, also known as digital eye strain, describes eye and vision problems caused by prolonged use of computers, tablets, e-readers, and mobile phones.
Many people experience eye discomfort and vision problems when looking at digital screens for long periods of time. The discomfort seems to increase with the amount of digital screen use.”
“Minimize discomfort caused by blue light and glare. Blue light from LED and fluorescent lighting, as well as screens, tablets and mobile devices, can negatively affect vision in the long term. Special lens tints and coatings can reduce the harmful effects of blue light.”
FOX21 News: How "blue light" affects children's eye health
https://youtu.be/k-MJuuT7uqI?si=zhS_JVaPq1tOSAlV&t=9
