In a hypothetical scenario, where a large, permanently manned craft is in a continual orbit, and natural sunlight cannot be used as the craft may keep moving and turning, artificial sunlight is used in the form of LED panels.
My question is this: Will the LEDs have any adverse effect on the human body? The LEDs are of the SoLED variety which have very low IR levels and almost nil UV light levels, have any adverse effects on the body? I suppose the lack of UV may cause some disturbance in Vitamin D and melanin levels. Is this valid? Would there be any other problems?
Yes. Natural sunlight doesn't have a good substituent.
Melatonin levels and circardian rhythms are directly affected by natural sunlight.
As far as LEDs goes, a french study concluded that blue light may have photochemical risks and affect our retina.
Sunlight can influence the breakdown of medicines in the body
A study from the Swedish medical university Karolinska Institutet has shown that the body's ability to break down medicines may be closely related to exposure to sunlight, and thus may vary with the seasons. The findings offer a completely new model to explain individual differences in the effects of drugs, and how the surroundings can influence the body's ability to deal with toxins.
The study will be published in the scientific journal Drug Metabolism & Disposition and is based on nearly 70,000 analyses from patients who have undergone regular monitoring of the levels of drugs in their blood. The drugs taken by these patients are used to suppress the immune system in association with organ transplants. Samples taken during the winter months were compared with those taken late in the summer.
A more detailed analysis showed that the concentrations of drugs such as tacrolimus and sirolimus, which are used to prevent rejection following transplantation, vary throughout the year in a manner that closely reflects changes in the level of vitamin D in the body. The ability of the body to form vitamin D depends on sunlight, and the highest levels in the patients taking part in the study were reached during that part of the year when the levels of the drugs were lowest.
The connection between sunlight, vitamin D and variations in drug concentration is believed to arise from the activation by vitamin D of the detoxification system of the liver by increasing the amount of an enzyme known as CYP3A4. This enzyme, in turn, is responsible for the breakdown of tacrolimus and sirolimus.
"If the breakdown capacity increases, then higher doses of a drug are normally required in order to achieve the same effect. More research will be needed to confirm the results, but CYP3A4 is considered to be the most important enzyme in drug turnover in the body, and the results may have significance for many drugs," says Jonatan Lindh at the Department of Laboratory Medicine and one of the scientists who carried out the study.
The effects of vitamin D on CYP3A4 have previously been demonstrated in experiments in cell cultures. But the study now to be published shows for the first time that the mechanism can play an important role in the pharmacological treatment of patients, and it shows for the first time that variation in exposure to sunlight may affect the sensitivity of individuals to drugs.
Materials provided by Karolinska Institutet. Note: Content may be edited for style and length.
1. Why is artificial light a concern?
Single envelope CFL
Artificial light is composed of visible light as well as some ultraviolet (UV) and infrared (IR) radiations, and there is a concern that the emission levels of some lamps could be harmful for the skin and the eyes. Both natural and artificial light can also disrupt the human body clock and the hormonal system, and this can cause health problems. The ultraviolet and the blue components of light have the greatest potential to cause harm.
Some people with diseases that make them sensitive to light claim that the energy-saving lamps (mainly compact fluorescent lamps (CFLs) and light emitting diodes (LEDs)) that have been brought to replace incandescent lamps, make their symptoms worse and play a role in a wide range of diseases. They also argue that protective measures such as covering the lamps with a second glass envelope (which decreases the UV-emissions), are ineffective.
Using some types of CFLs for long periods of time at close distances may expose users to levels of UV nearing the limits set to protect workers from skin and eye damage. More.
The effects of light on the human body
PIP: This article explores the influences of light on human health and suggests that exposure to artificial light may have harmful effects. The effects of ligght on mammalian tissue are either direct or indirect, depending on whether the immediate cause is a photochemical reaction within the tissue or a neural or neuroendocrine signal generated by a photoreceptor cell. Light exerts an indirect effect on the ovaries of rats and this effect is mediated by photoceptive cells in the retina. The light cycles involved in night and day and changing day lenght appear to be associated with rhythmic changes in mammalian biological functions such as body temperature. Light levels and rhythms also influence the maturation and subsequent cyclic activity in the gonads of mammals, with the particular response seemingly dependent on whether the species ovulated once a year or at regular intervals. Ovulation can be accelerated in diurnally active, monestrous animals by exposing them to artificially long days. Pineal activity in rats can be suppressed by exposing the animals continuously to light. Such findings on the multiple and disparate effects of light suggest the view that health considerations should be incorporated into the design of light environments. The illumination provided by artificial indoor lighting is often less than 10% of the light normally available outdoors. It is urged that decisions on lighting be based on knowledge of man's biological needs as well as economic and technoloical considerations.
Shining Light on What Natural Light Does For Your Body
Of course using natural light instead of artificial light reduces energy consumption and lowers your electricity bill. But did you know how important natural light is important to your productivity and overall health? Check out all the benefits of seeking sunlight instead of flipping on the light switch.
Natural light boosts your body’s vitamin D storage
Vitamin D is important for absorbing calcium and promoting bone growth, as well as helping prevent certain types of cancers, heart disease, depression and weight gain. Yet, many Americans have a vitamin D deficiency due to a lack of outdoor sun exposure. So get outside since scientists suggest that Vitamin D may be helpful in treating many different disorders and diseases, such as autism, cancer, diabetes, chronic pain and depression.
Natural light leads to higher productivity
A study by the Swiss Federal Institute of Technology found that employees working in natural light recorded higher levels of energy than those working under artificial light. Another study showed 40 percent higher sales at checkout counters located beneath skylights. This data confirms what many studies have shown: natural light leads to enhanced productivity.
Natural light benefits vision
Computer screens, smart phones and florescent light can cause eye strain that can lead to permanent eye damage. Natural light has been shown to lower the risk of nearsightedness in children and young adults by helping the eye produce dopamine, which aids in healthy eye development.
Natural light helps you sleep
Research shows that the amount of sunlight you receive during the day has a direct impact on how much sleep you get at night. Direct sunlight, especially early in the morning for at least half an hour, produces the most benefit for a good night’s sleep while artificial lighting has little to no effect. In fact, artificial light before bed and at night can increase the risk of type 2 diabetes, high blood pressure and cancer if you’re unable to consistently obtain quality sleep.
Natural light improves your mood
Did you know that there is a type of depression called Seasonal Affective Disorder, which affects many people in the winter when they do not receive enough sunlight? Scientists believe that the “happy” hormone called serotonin increases when nights are short and days are long. In fact, many psychiatrists recommend that people get out in the sunlight for at least 30 minutes a day to help prevent or treat depression.
So, put on some sunscreen, go outside and enjoy some spring weather. Your body will thank you.
Change Your State through simple, everyday actions.
Explore more sustainability tips related to food, energy, waste, water, wellness and travel.
Sunlight and sleep cycles
The importance of the Sun didn’t disappear when we stopped using sundials. It’s extremely important to our health, both physical and mental. Chris Smith spoke to science journalist Linda Geddes, author of the book Chasing the Sun about the impact the Sun has on our health.
Linda - Well, sunlight affects us in various ways. There's Vitamin D as you mentioned, but there's also its effects on our circadian rhythms. So in every cell of our bodies, we have these (close to, but not exactly) 24 hour rhythms - in everything from when we release hormones, to the chemistry of our brains, to the activity of our immune cells. And the way those rhythms are kept synchronised with the time of day outside is through the action of light hitting this subset of cells at the back of the eye. But also the timing of those clocks is influenced by when we see the light. Most people will identify as either 'owls' or 'larks': people who like to stay up late, or people who like to get up with the sunrise. Now if you see lots of bright light early in the morning, your circadian rhythms are going to be shifted earlier, so you're going to become more lark-like but if you're seeing light late at night in the evening and overnight, it's going to push you more towards being an owl. Genetics is also involved, so it's not just about light but light does have this influence.
Chris - There must be an influence, then, of the invention of the light bulb! Because we haven't had artificial light until relatively recently in human existence, in the last hundred years or so. So has there been a big shift then?
Linda - Well, if you send groups of people camping, you notice that their circadian rhythms shift a little bit earlier, so they become more lark-like. But if you go and. when I was researching, chasing the sun, I went and visited an Amish family in America, and they have a much more traditional relationship with light because they're not connected to the electric grid, and they too are much more lark-like. And if you ask. there are some Amish people who will identify as night owls, but if you ask them, "what time would you ideally get up, and what time would you ideally go to bed?" I spoke to one of these people, she said, "ideally, I'd like to stay up until maybe about 10:00 PM? I know it's really, really late, but that would be my choosing." And she'd like to sleep in until 7:00 AM!
Chris - But why is it a problem, then, fighting your clock, becoming more lark-like, or becoming more owl-like? Why is that a problem?
Linda - It's not a problem if you can choose when you get up and go to work. So if you're not feeling sleepy until midnight, 1:00 AM, and you've still got to get up for work or school at 7:00 AM, you're cutting short your sleep. And sleep is important for all sorts of. for your health, for both your physical and mental health.
Chris - So it's the sleep that's paying the price, and the health cost comes because of sleep paying the price, is what you're saying - both in terms of the physiological cost, because we know that people who are sleep deprived have all kinds of physiological problems, high blood pressure, other risks of other things like weight gain and so on - but also mental health, because if you're not sleeping restoratively, you're more likely to suffer in that respect?
Linda - Yes. But there's a second thing, which is that if you're constantly shifting your sleep timing and you're not having that strong light signal in the daytime, and that weak light signal at night, your internal clocks can become desynchronised. So your clock in your heart isn't quite on time and in keeping with the clock in your stomach or the clock in your brain, and you're getting this kind of spreading desynchrony around the body. And that has been shown to have an influence on health independently of sleep as well.
Chris - When you were writing the book, did you also look not just at day-to-day time, but year-to-year time? Because there's also this phenomenon of Seasonal Affective Disorder. I suspect as the Northern Hemisphere goes into summer and we're actually seeing some sunshine, a lot of people will suddenly start to say they feel enormously better for no reason, but it's down to the longer days and sunnier days. Have you looked at Seasonal Affective Disorder as well?
Linda - Yes, I have. And there's an interesting thing about the increasing days though, which is that you assume that the most depressing time of the year is the winter, but when it comes to suicides and especially violent suicide, you get a peak in late spring. And the leading theory for why that is, is that you're getting this increase in serotonin, which is a brain signalling chemical which is produced in response to light as well. That's interesting. But yes, certainly Seasonal Affective Disorder is a real thing. And one of the best cures for it is light therapy, which involves being exposed to bright light, first thing in the morning, and what that is doing is resynchronising your clock to the 24-hour clock outdoors on Earth.
Chris - Have we seen consequences of people being cooped up during lockdown then? And is that part of the reason why people have found it tough - because they've been divorced from that normal, strong solar stimulus to feel good?
Linda - Well, I'm sure it's not the only factor, but one symptom of this kind of this desynchrony and this flattening of the circadian rhythm is that you feel sleepier in the daytime and more awake at night. Independent of the circadian clock actually, those light sensitive cells at the back of the eye also feed into brain areas that control alertness and mood as well. So light is a brain stimulant, but there've been studies that have looked at the effect of exposing people to an hour of relatively low intensity blue light, and being exposed to an hour of that is equivalent to drinking several cups of coffee in terms of the 'alertness boost' it gives you. What I always do is I try and get outdoors first thing in the morning and get some of that bright light first thing, but also try to get outside regularly during the day, just for a kind of light snack.
Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases
Routine exposure to artificial light at night (ALAN) in work, home, and community settings is linked with increased risk of breast and prostate cancer (BC, PC) in normally sighted women and men, the hypothesized biological rhythm mechanisms being frequent nocturnal melatonin synthesis suppression, circadian time structure (CTS) desynchronization, and sleep/wake cycle disruption with sleep deprivation. ALAN-induced perturbation of the CTS melatonin synchronizer signal is communicated maternally at the very onset of life and after birth via breast or artificial formula feedings. Nighttime use of personal computers, mobile phones, electronic tablets, televisions, and the like--now epidemic in adolescents and adults and highly prevalent in pre-school and school-aged children--is a new source of ALAN. However, ALAN exposure occurs concomitantly with almost complete absence of daytime sunlight, whose blue-violet (446-484 nm λ) spectrum synchronizes the CTS and whose UV-B (290-315 nm λ) spectrum stimulates vitamin D synthesis. Under natural conditions and clear skies, day/night and annual cycles of UV-B irradiation drive corresponding periodicities in vitamin D synthesis and numerous bioprocesses regulated by active metabolites augment and strengthen the biological time structure. Vitamin D insufficiency and deficiency are widespread in children and adults in developed and developing countries as a consequence of inadequate sunlight exposure. Past epidemiologic studies have focused either on exposure to too little daytime UV-B or too much ALAN, respectively, on vitamin D deficiency/insufficiency or melatonin suppression in relation to risk of cancer and other, e.g., psychiatric, hypertensive, cardiac, and vascular, so-called, diseases of civilization. The observed elevated incidence of medical conditions the two are alleged to influence through many complementary bioprocesses of cells, tissues, and organs led us to examine effects of the totality of the artificial light environment in which humans reside today. Never have chronobiologic or epidemiologic investigations comprehensively researched the potentially deleterious consequences of the combination of suppressed vitamin D plus melatonin synthesis due to life in today's man-made artificial light environment, which in our opinion is long overdue.
Keywords: Artificial light at night cancer circadian time structure development and disruption melatonin sleep/wake cycle disturbance sunlight vitamin D vitamin D deficiency.
The development of artificial lighting technologies over the centuries has transformed human civilization and shaped the way we live. The world has become awash with artificial lighting both during the day and at night, indoors and outdoors, from office buildings to streetlights. Before Edison’s invention of the light bulb (1879), people spent most of their time outdoors, receiving adequate daily doses of natural, full-spectrum sunlight during the day while spending their evenings and nights in relative darkness. With the growing availability of artificial lighting, people are spending an increasing amount of time inside under artificial lighting and consequently reducing the amount of time they are exposed to natural full-spectrum light during the day and darkness during the night. Around 99% of the population of the United States and Europe, and 62% of the world’s remaining population, are exposed to artificial light at night (ALAN), the amount of which is increasing rapidly each year . Not only are humans but also fauna and flora are exposed to ALAN, with ensuing environmental consequences. ALAN is one of the fastest growing and most common kinds of environmental pollution. The effects of ALAN on fauna have been well defined and documented, and almost only negative effects have been reported. ALAN affects behavior, foraging, reproduction, communication, breeding cycles and the habitat of many nocturnal species , , , including invertebrates  amphibians , birds , bats , turtles , , , fish  and reptiles . On the other hand, the impact of ALAN on flora is less documented a review on the topic is reported by Briggs . Exposure to artificial light prevents many trees from adjusting to seasonal variations. The presence of ALAN stimulates photosynthesis at a time when photosynthesis does not normally occur. Similar to humans and animals, plants require a specific cycle of light/darkness in order to grow healthily. Light affects several plant processes, such as seed germination, stem elongation, leaf expansion, conversion from a vegetative to a flowering state, flower development, fruit development, cessation of leaf production (bud dormancy) and leaf senescence and abscission for all these processes, the duration, wavelength and intensity of the light are crucial . Some of this knowledge is commonly used by the greenhouse industry to promote flowering and growth, and to stimulate fruit, vegetable and plant production. High intensity discharge (HID) lamps are popular for a large area of lighting applications in horticulture.
Artificial light is sometimes beneficial and sometimes detrimental to human health. Light has a profound impact on circadian systems and physiological functions. Because of this major impact and the growth in ALAN, there is evidence for a strong link between exposure to ALAN and disease. ALAN may be associated with an increased risk of breast cancer , , , , , , prostate and colorectal cancer , , and may also cause obesity , , diabetes  and depression . Kloog et al.  report that women have 30–50% higher risk of breast cancer in the countries with the highest exposure to ALAN compared to those with the lowest exposure. One efficient way to monitor the effect of light on circadian systems is to evaluate melatonin suppression in biofluids. Melatonin, also called the sleeping hormone, is produced by the pineal gland and is released mainly during the night. Light induces a decrease in pineal melatonin hormone production and secretion and it may also induce a phase shift in daily rhythms . The discovery of a novel non-visual photoreceptor, with the photopigment melanopsin acting on our circadian function , , has changed the understanding of that mechanism. Melanopsin responds to light by decreasing pineal melatonin hormone production, with a maximum spectral sensitivity at blue wavelengths. Two light variables, intensity and wavelength , are responsible for the suppression of melatonin, and an illuminance of only 1.5 lux may disrupt circadian rhythms . According to our measurements, taken in Sherbrooke (Canada), an illuminance of ∼2 lux is frequently encountered in urban bedrooms. Moreover, the human circadian system responds to millisecond flashes of light, delaying pineal melatonin production .
Indoor artificial lighting can be beneficial to humans. For example, light therapy is commonly prescribed by doctors against seasonal affective disorder . It has also been shown that blue-enriched light during the day increases performance, vigilance and sleeping patterns . Exposure to compact fluorescent light (CFL) at a correlated color temperature (CCT) of 6500 K (blue-enriched light) induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort . These results suggest that the selection of CFL with different CCT has a significant impact on circadian physiology and cognitive performance at home and at work. Finally, the availability of electronic devices with backlit screens, which are often used at night, is rapidly increasing throughout the world. In comparison with backlit liquid crystal display (LCD), evening exposure to a light emitting diode (LED)-backlit computer screen (blue-enriched light) resulted in attenuated salivary melatonin and sleepiness levels, with a concomitant increase in cognitive performance associated with sustained attention and with working and declarative memory . With the progress of LED technologies, it will be important to build electronic device screens in accordance with the circadian cycle .
Since the 1960s, outdoor artificial lighting has progressively changed from incandescent-bulbs (orange-yellow color, see Fig. 1) to a high pressure sodium form (HPS, orange) and more recently to LED (blue-enriched white light). The indoor artificial lighting that is most used is cool-white fluorescent lighting (FL) for public areas and incandescent, halogen and CFL bulbs for private areas with a large span of CCT. In lighting engineering, lower CCT (CCT<5000 K) is often called warm white light while high CCT (CCT>5000 K) is called cool white light. The use of artificially generated full spectrum daylight for human activities is not common, but they are used in the field of light therapy, greenhouse lighting and for pet shops. This kind of light is reputed to mimic natural sunlight, but it is not exact in this, as will be discussed later.
On that figure, the spectral locus, which is the line for monochromatic light, is shown by the thick black line. Thin black lines indicate color zones. Black squares show monochromatic values, while small black circles are lamps.
Reduction in star visibility, one of the best known impacts of outdoor ALAN, has been identified by astronomers. A first abatement for the protection of night sky quality over professional astronomical observatories was adopted in 1958 in the vicinity of Flagstaff, AZ, USA. Astronomers have always preferred the use of low pressure sodium (LPS) lamps. This technology shows quasi-monochromatic spectral power distribution (SPD) in the orange part of the visible spectrum. This kind of SPD is easy to filter out using optical filters and its color is not very efficient in terms of atmospheric scattering. In fact, when light travels into the atmosphere, it is partly scattered by molecules and aerosols and can be redirected toward an observer looking at the stars. This astronomical light pollution is then competing with the faint light coming from the universe. According to the Mie and Rayleigh scattering theories, blue light is scattered more efficiently than other colors (e.g. blue scattering is about one order of magnitude more efficient than red scattering).
The first main difference between daytime and nighttime natural light is the intensity level, since sunlight, starlight and moonlight are not so different in terms of their relative SPD. Sunlight is around five to nine orders of magnitude brighter than typical ancestral nighttime illumination (natural or human-made). In modern times, nighttime artificial illumination in lit areas is typically four orders of magnitude higher than illumination from a natural starry sky without moonlight, and around one to two orders of magnitude higher in comparison to full moonlight illumination. Light from wood/oil burning, which was the most intense source of human-made lighting for centuries, contains a very low blue light contribution in comparison to sunlight. Nowadays, human-made light shows important differences in comparison to wood/oil burning and the Sun’s SPD. The most significant nighttime natural lights, such as those from the stars, moon and wood/oil burning, can be described as a quasi black body spectrum showing a predominant continuum SPD, while many modern artificial lights include the addition of discrete spectral lines with a very low continuum contribution. Natural light contains all wavelengths of the visible spectrum while some artificial lights contain only a subset or are dominated by a few spectral lines. Artificially generated full spectrum daylight lamps, which were designed to approximate to sunlight, contain essentially all the wavelengths of the visible spectrum but with relatively important discrete spectral lines superimposed to a continuum. Tungsten incandescent technology SPDs (halogen tungsten incandescent and standard tungsten incandescent) are similar to natural light in terms of the relative importance of the continuum, but with a lower CCT compared to the sun, moon and the brightest stars. In other words, tungsten-based SPD shows a higher relative red contribution compared to the sun. Even if, with passing time, humans are increasing their light spill into the environment, not enough consideration has been given to the development of lighting devices that have an SPD comparable to natural light (either daytime or nighttime).
In the field of lighting engineering, the parameters used to describe light spectra are very crude and do not characterize SPD in detail. As an example, CCT and the color rendering index (CRI) are often used, but both parameters refer to a black body style of spectrum. CCT is the black body temperature that gives the same color sensation to the average human eye. CRI gives information concerning to what extent a lamp spectrum can be compared to a black body SPD in terms of its color rendering. A CRI value of 100 means that the lamp SPD is a perfect black body spectrum. CRI can be evaluated by comparing the color rendering of the source with a black body of the same CCT. This is why tungsten halogen shows CRI∼100, which is the optimal value of CRI. As stated above, most modern artificial light SPDs are very far from black body values. To obtain a good approximation of human eye color perception under sunlight, we need a CRI of 100 and a CCT of around 5800 K. One technology that is not far from this ideal target is the ceramic metal halide lamp (CCT∼5400 and CRI∼96), if we ignore spectral lines superimposed on the continuum spectrum.
Recently, LED technology from the field of solid state physics has been introduced to the lighting industry. LED emits a quasi-monochromatic SPD with a typical full width at half maximum (FWHM) of the order of 30 nm and a nominal wavelength depending on the material used to make the diode junction. Nowadays, the most efficient LEDs are the blue ones with a nominal wavelength ranging from 440 nm to 480 nm. Such light have of course a CCT and CRI that are very far from natural solar radiation. To overcome this drawback, a phosphorous material is placed between the blue LED and the observer. The role of that phosphorous material is to expand the narrow SPD of the blue LED into a broad band SPD. The resultant light is almost white but, when observing it with a spectrometer, one can clearly see that the white LED SPD can be described as including the addition of a broadband yellowish SPD with a significant remaining narrow band blue SPD.
The impact of artificial light on photosynthesis, on star visibility and on melatonin suppression is closely related to the concordance of the given spectral sensitivity of the phenomena being considered with the spectrum of the light. As an example, the photosynthesis action spectrum (PAS), or , which represents the efficiency of each wavelength in inducing photosynthesis for averaged vegetable species, shows two peaks: one in the blue region at around 450 nm and the other in the red part of the spectrum at around 660 nm (see Fig. 2). Basically this means that an artificial light having a significant emission around these wavelengths is more likely to interfere with photosynthesis, especially during the night when there is no solar light. White LEDs are somewhat problematic for nighttime photosynthesis because their blue peak fits almost perfectly with the blue sensitivity peak of PAS.
The same kind of analysis can be made to estimate: 1- the impact of ALAN on star visibility by considering the low illumination eye spectral sensitivity (scotopic response), and 2- the potential impact of artificial light on circadian cycle disruption using the melatonin suppression action spectrum (MSAS).
In this paper, we will introduce three new parameters or indices to characterize a light spectrum in terms of its potential impact on respective biological processes: 1- melatonin suppression, 2- photosynthesis, and 3- scotopic vision. Our indices are intended to separate SPD from other factors acting on the given biological process. As an example, a minimum illumination is required to induce circadian cycle disruption, but our new index ignores this minimum illumination level. By using such an index, we will therefore have to assume that all other variables known to have an impact on the given biological process are favorable. In this way, the indices only deal with the potential impact of SPD shape. After defining the indices, we apply them to a variety of existing lighting technologies. We finally calculate the impact of atmospheric light scattering on indices values as a function of the distance between the light source and the observer, with and without cloud cover. All comparisons are made considering a constant lumen output for each lamp.
Sunlight Makes You Skinny & Blue Light Makes You Fat: 11 Ways To Biohack Light To Optimize Your Body & Brain.
After all, light is just a wave of energy that signifies the absence of darkness, right? Fact is, light has a profound impact on human biology, for better or worse. In my last article on sleep, you learned plenty about the effects of artificial light and blue light on circadian rhythm and sleep, and in other articles, I've filled you in on biohacks such as photobiomodulation, near infrared, far infrared, UVA and UVB, including: How Modern Lighting Can Destroy Your Sleep, Your Eyes & Your Health, The Ultimate Guide To Biohacking Your Testosterone, How To Use Low Level Light Therapy and Intranasal Light Therapy For Athletic Performance, Cognitive Enhancement & More. & What’s The Healthiest Way To Tan
But the effects of light go far beyond its potential for positively hacking sleep or enhancing recovery, especially when it comes to the potential for artificial light to damage your overall wellness. The negative health impact of artificial light sources on endocrine and cellular levels in humans includes the risk of cataracts, blindness, age-related macular degeneration, mitochondrial dysfunction, metabolic disorders, disrupted circadian biology and sleep, cancer, heart disease and more.
For example, multiple recent studies have reported that exposure to artificial light can cause negative health effects, such as breast cancer, circadian phase disruption and sleep disorders. One 2015 study reviewed 85 scientific articles and showed that outdoor artificial lights (e.g. street lamps, outdoor porch lights, etc.) are a risk factor for breast cancer and that indoor artificial light intensity elevated this risk. This same study also showed that exposure to artificial bright light during nighttime suppresses melatonin secretion and increases sleep onset latency and increases alertness and that the circadian misalignment caused by artificial light exposure can have significant negative effects on psychological, cardiovascular and metabolic functions.
One perfect example of the effects of modern light on human biology is that of LED (light-emitting diode), which is rapidly replacing compact fluorescent (CFL) bulb, primarily because LEDs do not contain mercury like CFLs and they’re far more energy efficient. LED lighting is used in aviation lighting, automotive headlamps, emergency vehicle lighting, advertising, traffic signals, camera flashes, and general lighting. Large-area LED displays are also used in stadiums, dynamic decorative displays, and dynamic message signs on freeways. But LED’s pose significant environmental risks and toxicity hazards due to their high amount of arsenic, copper, nickel, lead, iron, and silver.
But LED’s can also cause severe retinal damage to the photoreceptors in your eye and have even been shown to induce necrosis (cell death!) in eye tissue. The American Medical Association even put out an official statement warning of the health and safety issues associated with white LED street lamps. Things get even worse once dimming and color changing features are introduced into LED lighting, which is a common lighting feature in modern “smart homes”.
The reason for this is that LED lamps are a form of digital lighting (in contrast, the incandescent light bulbs and halogens light bulbs you’ll learn about momentarily are analog thermal light sources). In a color changing system that allows you to adjust the dim or color of the lights, there are typically three different LED sources: red, green and blue. The intensity of these three sources has to be changed to achieve different colors, and this feature must be controlled digitally via a mechanism called pulse-width modulation. This means the LEDs rapidly alternate between switching to full intensity and then switching off over and over again, resulting in a lighting phenomenon called “flicker”, something I recently discovered during my Building Biology analysis occurs quite a bit even in my own biologically friendly home (influencing me to make some of the lighting changes you'll read about later in this article) and something that I've also learned quite a bit about from my friend Dr. Joe Mercola.
Even though it appears to your naked eye that the LEDs really aren’t changing color or intensity that much, your retina perceives this flicker, and you can often observe this phenomenon if you use an older camera, or a device called a “flicker detector” to record an LED light in your house or an LED backlit computer monitor. Unfortunately, this trick doesn’t work with newer cameras and smartphones, which have a built-in algorithm that detect the flicker frequency and automatically change the shutter speed to improve the recording quality. However, I’ve found that by switching my iPhone to slow-motion video recording, I can often detect flicker in a monitor or light. Ultimately, the problem is this: research has shown that this flicker can irreparably damage the photoreceptor cells in the eye's retina, resulting in issues such as headaches, poor eyesight, brain fog, lack of focus, increased risk of cataracts and sleep disruptions.
Unfortunately, energy saving lamps such as compact fluorescent lamps (CFLs) can also cause similar issues and can induce oxidative stress damage that affects not only the eyes but also sensitive photoreceptors on many other areas of the skin, along with endocrine and hormonal damage.
But light can be good too and in fact, the therapeutic use of full spectrum light – also known as “photobiology” – offers many surprising health benefits. For example, in the 1700's, scientist-inventor Andreas Gärtner, built the first phototherapeutical device, which was a foldable hollow mirror he could use to concentrate sunlight onto the aching joints of patients. A gold leaf on the mirror absorbed UV radiation from sunlight, then transformed this light into near-infrared and red wavelengths very similar to those used in modern times by people who use infrared saunas to manage joint pain. , which is beneficial because it can penetrate deeply into the tissue. In the 1800's, a General Augustus Pleasonton published the book “Influence of the Blue Ray of the Sunlight“, in which he describes “Influence Of The Blue Ray of Sunlight and Blue Colour Of The Sky In Developing Animal And Vegetable Life And In Restoring Health From Acute And Chronic Disorders To Humans And Domestic Animals”. In the late 1870's, Dr. Edwin Dwight Babbitt published his book, “Principles of Light and Color“, reporting on research in which he used colored light on different parts of the human body to elicit therapeutic results. In 1897, Indian physician Dinshah Ghadiali used chromotherapy in the form of indigo-colored light as a treatment for gastric inflammation and colitis, and late 19th century Niels Ryberg Finsen of Denmark, who was awarded the Nobel Prize for Physiology in 1903, used red light to treat smallpox, and other light spectrums to address chronic disease such as tuberculosis. In the decades following, Finsen phototherapy became more developed as a cutting-edge therapeutic intervention in modern medicine, including the groundbreaking book “Light Therapeutics” by Dr. John Harvey Kellogg and work by Dr. Oscar Bernhard, a Swiss surgeon who used heliotherapy (sun therapy) during surgeries.
Light can drastically affect our metabolism too. For example, the master fuel sensor in our cells called mTOR (“mammalian target of rapamycin”) facilitates protein synthesis and growth while inhibiting internal recycling of used or damaged cells. Plants and humans grow more in the summertime because there is not only more food abundance but usually more natural light too, which can activate mTOR. But your body needs a darkness – a winter, so to speak. The master fuel sensor in the winter, and in darkness, is AMP-0activated protein kinase (AMPK) which optimizes energy efficiency and stimulates recycling of cellular materials. This cycle happens during the night. Now, consider what happens if you are in a constant stage of light: your hormones and metabolism shift towards constant mTOR activation growth and anabolism – which is generally associated, when in excess, with issues such as cancer and shortened lifespan. On the flipside, by introducing periods of darkness (along with, ideally, fasting), you strike a balance between constant anabolism with zero cellular cleanup and smart catabolism with adequate time for natural cell turnover.
So how can you mitigate the damage of the wrong kind of light and maximize the benefits of the right kind of light? You're about to find out, along with how sunlight makes you skinny, blue light makes you fat and 11 ways to optimize light in your home and office environment.
11 Ways To Biohack Light To Optimize Your Body & Brain.
#1: Choose Your Lighting Carefully.
One way to ensure you are purchasing a healthier lightbulb is to look at at a value on the light label or box called the Color Rendering Index (CRI). CRI is a quantitative measure of the ability of a light source to reveal the colors of various objects accurately in comparison with an ideal or natural light source. For example, sunlight, incandescent light bulbs and candles all have a CRI of 100. When purchasing LED, look for an R9 (full red spectrum) CRI of close to 97, which is the highest CRI you are likely going to be able to find and can get you as close as possible to natural light. You also need to look at the color temperature of the light, which is the temperature of the light expressed in Kelvin (K) degrees. For example, the sun has a physical color temperature of 5,500 K, and a correlated color temperature (how the light source appears to the human eye, of about 2,700K. So although many LED’s have a color temperature of up to 6,500K, an ideal LED choice would be an LED with a color temperature as close as possible to 2,700K (in comparison, most incandescent lamps have a maximum color temperature of 3,000 K, since the light filament would melt if the temperature were any higher).
You can also consider the use of “biological LED”. For example, the company “ Lighting Science” produces a line of biological bulbs that give off light meant to complement the circadian rhythm, not disrupt it. The light that emanates from Lighting Science’s Sleepy Baby bulb, for example, does not interfere with melatonin production, the hormone that helps you and your baby sleep, and is designed to be as close to candlelight as possible. In contrast, their GoodDay spectrum of light is engineered to provide light energy largely missing from conventional LED, fluorescent and incandescent sources, specifically providing a rich white illumination with high color rendering inspired by morning sunlight that supports alertness, mood and performance. Unfortunately, while these light bulbs are a decent option for “customizing” certain areas of your home to have high or low amounts of blue light depending on whether that area of the home is a “waking” area (e.g. office, gym, garage) vs. a “sleeping” area (e.g. bedroom, master bathroom, etc.), they still do produce a significant amount of flicker based on both my own testing and the testing of the building biologist I hired to audit my home.
For the ultimate solution, although it can be more expensive and far less energy efficient, I recommend switching as many lightbulbs in your home and office as possible to A) the old-school style of clear incandescent bulbs, preferably without any coating (which changes the beneficial wavelengths) B) a candlelight-style organic light emitting diode (OLED), which is a human-friendly type of lighting because it is blue-hazard-free and has a low correlated color temperature (CCT) illumination, which means the candlelight style is deprived of high-energy blue radiation, and it can be used for a much longer duration than normal LED’s without causing retinal damage.
If you decide to go with incandescent, many incandescents are not clear, but instead coated with white to make them more aesthetically pleasing. Steer clear of these, and instead choose a 2,700 K incandescent light bulb or a low-voltage halogen lamp . The one benefit of the latter is that low-voltage halogen lights are very energy efficient compared to a standard incandescent lamp. However, most halogens operate on an alternating current (AC), which generates a large amount of dirty electricity, so you must use a direct current (DC) transformer with them. The problem is that to do this, you need an inverter switching power supply to convert AC to DC, and this can cause high voltage transients (dirty electricity) and relatively high electrical fields, both of which were measured by my friend Dr. Mercola when he tried to pull this off. So the only way to make a halogen lighting solution work is to go off-grid and switch your entire house to all DC power, or to use solar panels with no AC inverter installed, and used the solar power battery to run the halogens. I suspect this is too much trouble for most folks, and because of that, a limited use of biological LED along with either low-temperature incandescent bulbs or blue-hazard-free candlelight OLED lighting appears to be the best option.
#2: Get Morning Sun
Unless you’re trying to send your body a message that it “isn’t morning yet” to shift your circadian rhythm forward (see my last big article on sleep), you should actually expose yourself to as much natural sunlight as possible first thing in the morning. In fact, the more sun you get in the morning, the more melatonin you make at night. A morning, fasted walk in the sunshine is one of the best ways to optimize your overall health, and the full spectrum of UVA, UVB and near and far infrared from sunlight can also mitigate some of the damage of artificial light the rest of the day.
Interestingly, based on research by my friend Dr. Chris Masterjohn, it turns out that if you are deficient in the fat-soluble vitamins A and D, your photoreceptors become less sensitive and the strategy of getting adequate sunlight becomes less effective – so be sure to implement everything that makes sunlight able to charge your internal battery, including not only a diet rich in healthy fats, but also high in minerals, clean, pure water and frequent skin contact with the planet Earth. This is also yet another reason I am a fan of daily use of Kion Omega brand of fish oil, because it contains astaxanthin, which can protect photoreceptors from oxidative damage generated by artificial light!
#3: Use Blue Light Blockers.
Seven years ago, in an attempt to minimize the slight headache and eye discomfort I often experienced after spending long periods of daytime work on my computer, I purchased my first pair of “biohacked” glasses from a company called Gunnar. While these glasses significantly reduced my exposure to monitor flicker and even allowed me to wander through malls and grocery stores without being bothered as much by the harsh artificial lighting, blue light blocking technology has come a long way since then. For example, many companies, such as Amber (code: GREENFIELD), Felix and Swannies (code: GREEN10), now produce untinted, anti-glare glasses that can block the higher range of the blue light spectrum, and other brands, such as Spektrum, produce slightly tinted glasses that reduce even more of the blue light spectrum. Gunnar and Swannies now make yellow-tinted glasses that block most blue light, and Ra (code: BEN 10), Uvex and True Dark make orange and red-tinted glasses that block all blue light. I personally wear clear or yellow lenses for daytime computer work, nighttime dinners out or driving at night, then switch to the more effective but far less attractive orange or red lenses for the evening at home. If you want to get very specific with blocking the most harmful wavelengths of light, you should check that the glasses block the spectrum of 400-485nm (The Ra glasses are an example of a lens that blocks that specific spectrum).
#4: Avoid Artificial Light Not Only At Night, But In The Morning Too.
You’ll often hear that you should be careful with isolated and concentrated sources of blue light at night, but this rule applies to the morning too. Especially until you’ve gotten out into the sunlight, you should avoid artificial light as much as possible in the morning, particularly by limiting harsh, concentrated sources of blue light such as artificial home and office lighting or bright screens, and by instead opening curtains to allow as much natural light into the home and office as possible. In addition, you’ll often find me wearing blue light blocking glasses for the first couple hours of the morning, and avoid turning on the kitchen lights, bedroom lights, etc. unless absolutely necessary (trust me: making a big cup of hot coffee in the dark isn’t a good idea).
#5: Use Red Light In The Evening.
For the bedroom, consider red incandescent bulbs, particularly in the light fixtures near the bed. Candles are also an excellent option for both the bedroom and the dinner table, although you must choose fragrance-free, natural palm or beeswax candles, since many modern candles are riddled with paraffin, soy, toxic dyes and fragrances. If your phone or e-reader has the option, always switch it to night mode or, better yet, red light mode in the evening. Here's exactly how to do”The Hidden Smartphone Red Screen Trick”.
#6: Install IrisTech On All Monitors.
I first became aware of IrisTech software when I interviewed a 20-year-old, brilliant Bulgarian computer programmer named Daniel Georgiev on my podcast. Daniel invented a special piece of software that goes far beyond the blue-light blocking computer software called “F.lux” that many people are already familiar with. IrisTech controls the brightness of the monitor with the help of your computer’s video card, allows you to have adequate brightness without monitor flicker, reduces the color temperature of your monitor, optimizes screen pulsations to reduce eye strain, adjusts the brightness of your screen to the light around you, and even automatically adjusts your computer monitor’s settings based on the sun’s position wherever you happen to be in the world. It has settings for pre-sleep, reading, programming, movies and many others, and even allows you to receive pop-up reminders for activities such as eye exercises and stretching. Click here to get IrisTech.
#7: Use An Anti-Glare Computer Monitor.
Fancy, modern LCD monitors are not flicker-free, even though many people think they are because they don’t seem to appear as harsh as older computer monitors. These LCD monitors originally started out by using something called CCFL (cold cathode fluorescent lamps) as a backlight source for the monitor, but in recent years manufacturers have shifted to using LEDs (light emitting diodes). If you have one of those thin monitors, then you probably have an LCD monitor with LED, and if you are unsure, you can check the model number on the backside of the monitor and Google it. Due to the way brightness is controlled on LED backlights, it produces the same LED light flicker you’ve already learned about. The monitor I use is an Eizo FlexScan EV series, which regulates brightness and makes flicker unperceivable, without any drawbacks such as compromised color stability. It allows you to lower the typical factory preset color temperature setting of 6,500 K down to the more natural 2,700K and also has a “Paper Mode” feature, which produces long reddish wavelengths and reduces the amount of blue light from the monitor. The Eizo monitors also have a non-glare screen, which reduces eye fatigue by dissipating reflective light that otherwise makes the screen difficult to view.
#8: Use Light-blocking Tape Or Stickers.
Even if you are blocking light from reaching your eyes at night by using blue light blocking glasses, a sleep mask, black-out curtains, etc., you still need to be cognizant of items in your bedroom that produce LED lights, such as televisions, clocks, power strips or computer chargers. This is because even if your eyes are covered, your skin has photoreceptors that can detect all these sources of light. Even if you have mitigated all light sources in your own bedroom, walking into any hotel room at night presents you with a veritable Christmas tree-like lighting experience. at hotels. Fortunately, you can easily purchase simple and affordable light blocking pieces of tape, such as “LightDims” that are specially designed, removable tiny covers which act like sunglasses for irritating LEDs on electronics. They can dim or completely cover unwanted LED glare or flare in any room. You simply peel off a sticker and apply it to your electronics, keeping them functional while dimming annoying LEDs to a comfortable or completely unnoticeable level. If you ever feel like you are being bombarded with LED's or external sources of light in any room – even when you feel like you’ve already shut everything off, these stickers work perfectly.
OK, I'm going to stop for a second and go down a rabbit hole here: why on earth would you want to limit the amount of light that your skin is exposed to? Frankly, because your skin is an eye.
See, in the animal kingdom, light-sensing photoreceptors that go far beyond the eyes are actually quite prevalent. Most of the photoreceptors scientists have found outside the eyes are usually located in the brain or the nerves (or in insects, on the antennae).
But a number of different photoreceptors have been found on animal skin too, particularly in active color-changing cells or skin organs called chromatophores. You likely know these better as the black, brown or brightly colored spots on fish, crabs, frogs, octopus and squid. In many cases, animals can control these chromatophores for camouflage (to match the color and pattern of a background) or to produce colorful signals for either aggression or attracting a mate.
But aside those photoreceptors utilized for camouflage or mate attraction, what in the world is the purpose of all the other photoreceptors? It appears that they help to maintain a normal circadian rhythm, even without precise knowledge of a light source’s location in space or time. These circadian rhythms include the timing of daily cycles of alertness, sleep and wake, mood, appetite, hormone regulation and body temperature. In some animals, they have a quite different task: magnetoreception, which is the ability to detect the Earth’s magnetic field for the purposes of finding direction – an underlying mechanism for orientation in, for example, birds, bees and cockroaches.
But it turns out that people have nonvisual photoreceptors too. With the discovery of light-sensitive retinal cells in addition to rods and cones in mammalian retinas, it has become obvious that humans must use some sort of nonvisual pathway for at least some of the control of behavior and function. For example, pupil size and circadian rhythms vary with changing light, even in functionally blind humans who have lost all rods and cones due to genetic disorders. Recent research with rodents at Johns Hopkins University suggests that these nonvisual pathways can even regulate mood and learning ability.
It turns out that these photoreceptors in humans go far beyond the eyes and that, just like animals, they are found in our skin, subcutaneous fat, central nervous system and host of other areas in our body. Because the human skin is exposed to a wide range of light wavelengths, one recent study investigated whether opsins, the light-activated photoreceptors that mediate photoreception in the eye, are expressed in the skin to potentially serve as “photosensors”. They showed that four major opsins are indeed expressed in two major human skin cell types: melanocytes and keratinocytes and that these opsins are capable of initiating light-induced signaling pathways to the rest of the body.
Another recent study at Johns Hopkins University discovered melanopsin inside blood vessels. Melanopsin is another one of the photoreceptors used in retinal nonvisual photoreception. The researchers found that this light-sensitive protein can regulate blood vessel contraction and relaxation, and can also be damaged by exposure to blue light. Interestingly, melanopsin tends to be much weaker and more susceptible to this damage when fat-soluble Vitamins A and D are deficient.
Another recent finding backs up the fact that it is not only light falling on our eyes which determine our “circadian rhythms” – the body's internal clock. In this study, it was shown that shining a bright light on the skin (in this case, behind the knees) has the same effect as shining light on the retina when it comes to regulating our 24-hour circadian clock. Scientists suggest that one reason that humans have circadian rhythm photoreceptor on their skin is that when light falls on blood vessels near the skin, it increases the concentration of nitric oxide in the blood, which can significantly shift the circadian clock. This should be especially important to you when you learn this: blue light can penetrate skin as deep as blood vessels, which means that artificial light on your skin can directly affect your circadian rhythm.
Then there’s a photoreceptor protein called “neuropsin”, which is primarily found in the retina but is also located in the skin and is another of the light-sensitive pigments that have been found to help run the body’s master clock. Neuropsin responds to UV-A and violet light, while melanopsin seems more sensitive to blue and red light. This may partially explain why going out into the sun during the day (which activates neuropsin) may work so well for regulating your circadian rhythm.
Finally, it seems that these photoreceptors strongly interact with hormone production and fat burning too. In one study, researchers put some fat cells under lamps giving off visible light that simulated the sun for four hours and kept other samples in the dark. After two weeks, the fat cell groups showed remarkable differences, including fewer lipid droplets (these are the organelles that store fat), compared the cells that didn’t get any light. This means that exposure to adequate sunlight (on both the skin and the eyes) could actually cause your cells to store less fat – and based on a number of compelling studies, artificial light (especially blue light) may have the complete opposite effect!
If you want to take a deep dive into how profoundly light can interact with the skin, you should check out work of my former podcast guest Dr. Jack Kruse, who even talks about how light exposure to the eyes and the skin affects your carbohydrate sensitivity, thyroid activity, hormone production and much more.
Fascinating, eh? Alright, back to the light-hacking tips…
#9: Use Driftbox For Your TV.
The Driftbox is a small box that you plug into your TV. It removes a percentage of blue light from the content you watch, and allows you to view the TV screen at night with far less artificial light exposure. You can set how much blue you want to take out. For example, you can set it to remove 50% (or any percentage in increments of 10%) of all blue light over a period of one hour (that way, the transition is seamless and virtually unnoticeable if you’re watching a movie at night).
#10: Don’t Overuse Sunglasses.
Unless I’m trying to avoid snow blindness from a day of snowboarding on a glaring bright white slope or I’m at a windy beach getting sand blown in my face, you’ll rarely find me sporting sunglasses. Why? Our bodies are designed to be able to perfectly cope with sunlight. The retina in your eyes actually registers how bright it is, then secretes specific hormones to keep you safe from the sun. Specifically, sunlight stimulates your pituitary glands, via the optic nerve, to produce a hormone that triggers the melanocytes in your skin to produce more melanin, which allows you to tan and offers some protection from excess UV radiation. When you wear sunglasses, less sunlight reaches the optic nerve, and thus less protective melanin is made and the higher the risk of a carcinogenic and uncomfortable sunburn. However: if you don’t happen to have a set of blue light blocking glasses handy, there can be an advantage to “wearing sunglasses at night”, especially while driving: car headlamps are notorious sources of concentrated blue light from LED!
#11: Use Photobiomodulation Daily.
Photobiomodulation therapy involves using light of all wavelengths, including visible light, ultraviolet and red near-, mid- and far-infrared wavelengths to combat the effects of artificial light and to also elicit some surprising research-proven health benefits for the entire body. For example, blue light therapy has been shown to be good at relieving joint pain, although it can be harsh on the eyes and the circadian rhythm if you overdo it. Red light has a host of research proving it’s efficacy for relieving inflammation, balancing blood sugar, lowering fat deposition, improving macular degeneration, assisting with melatonin production, increasing blood flow to the brain, building stem cells in bone marrow, and even enhancing kidney and thyroid function. Perhaps most surprisingly, Olympic athletes are now using red light therapy devices as a performance-enhancing aid to increase time to exhaustion. One of the most commonly used wavelengths of light in photobiomodulation is near-infrared, which begins at about 750 nanometers (nm) and goes all the way into 1,200 nm. In the lower range, near-infrared penetrates beneath the skin, and at the high range, deep into the body, resulting in a significant release of nitric oxide and stimulation of mitochondrial pathways that assist with ATP production. Far-infrared is another spectrum frequently used in photobiomodulation, especially in the form of heat lamps or infrared saunas. It is absorbed by the water in your body, which is why it cannot penetrate as deeply as near infrared, but also has significant healing effects on the body, especially if you are well hydrated on some form of “structured water” while using it (read Gerald Pollack's book “The Fourth Phase of Water” for more on this) .
A word of warning: there appears to be a “Goldilocks effect” when it comes to photobiomodulation: most photobiomodulation devices use a power density that is between 10 and 20 milliwatts per square centimeter. That is the equivalent light dose of 1 joule per 100 seconds, and since approximately 10 joules is considered to be a therapeutic dose of light, you really don’t need to use photobiomodulation for much more than 20 minutes per day (depending on the power of the device you use and your distance from the device). In addition, all light emits a frequency, and it appears that the ideal frequency is 10-40 hertz – with higher frequencies potentially causing a negative biological effect. I personally use a photobiomodulation panel of clinical-grade red and near-infrared light called a JOOVV (placed near the standup desk in my office) for 20 minutes per day, along with a head-worn device called a “Vielight” (code: GREENFIELD) for 25 minutes every other day, and finally, a far infrared sauna for 30 minutes three times per week.
Ultimately, you should now realize how profound an impact light has on your biology, why sunlight can regulate hormones and metabolism to allow you to stay lean and healthy, while artificial light can do the opposite, and the best way to “use light” to your metabolic advantage. I hope this has been helpful to you. Do you have questions, thoughts or feedback for me on any of these light hacking tips you've discovered? Leave your comments below and one of us will reply!
Newly-Developed Electronic Artificial Skin Can Sense Touch, Pain and Heat
A team of researchers at RMIT University has developed electronic artificial skin that mimics the human body’s near-instant feedback response and can react to painful sensations with the same lighting speed that nerve signals travel to the brain.
The skin-like sensing prototype device, made with stretchable electronics. Image credit: RMIT University.
Skin is the largest human sensory organ covering the entire body.
Every region of the skin is full of sensors, which detect external stimuli and actively measure the level of such stimuli.
Sensory skin feedback is indicative of health. For instance, pin pricks are used to study the response of a nervous system to evaluate degree of paralysis from nerve damage.
Artificial skin receptors that demonstrate such feedback ability are integral to advancements in healthcare and intelligent robotics.
Such receptors can replace damaged receptors, augment sensation of specific stimuli, or serve as the feedback mechanism for human-machine or machine-machine interfaces.
“Our pain-sensing prototype is a significant advance towards next-generation biomedical technologies and intelligent robotics,” said co-lead author Professor Madhu Bhaskaran, a researcher in the Functional Materials and Microsystems Research Group and the Micro Nano Research Facility at RMIT University.
“Skin is our body’s largest sensory organ, with complex features designed to send rapid-fire warning signals when anything hurts.”
“We’re sensing things all the time through the skin but our pain response only kicks in at a certain point, like when we touch something too hot or too sharp.”
“No electronic technologies have been able to realistically mimic that very human feeling of pain — until now.”
“Our artificial skin reacts instantly when pressure, heat or cold reach a painful threshold.”
“It’s a critical step forward in the future development of the sophisticated feedback systems that we need to deliver truly smart prosthetics and intelligent robotics.”
Professor Bhaskaran and her colleagues used three technologies in their research:
(i) stretchable electronics: combining oxide materials with biocompatible silicone to deliver transparent, unbreakable and wearable electronics as thin as a sticker
(ii) temperature-reactive coatings: self-modifying coatings 1,000 times thinner than a human hair based on a material that transforms in response to heat
(iii) brain-mimicking memory: electronic memory cells that imitate the way the brain uses long-term memory to recall and retain previous information.
The pressure sensor prototype combines stretchable electronics and long-term memory cells, the heat sensor brings together temperature-reactive coatings and memory, while the pain sensor integrates all three technologies.
“The memory cells in each prototype were responsible for triggering a response when the pressure, heat or pain reached a set threshold,” said first author Md. Ataur Rahman, also from the Functional Materials and Microsystems Research Group and the Micro Nano Research Facility at RMIT University.
“We’ve essentially created the first electronic somatosensors — replicating the key features of the body’s complex system of neurons, neural pathways and receptors that drive our perception of sensory stimuli.”
“While some existing technologies have used electrical signals to mimic different levels of pain, these new devices can react to real mechanical pressure, temperature and pain, and deliver the right electronic response.”
“It means our artificial skin knows the difference between gently touching a pin with your finger or accidentally stabbing yourself with it — a critical distinction that has never been achieved before electronically.”
The team’s paper was published in the journal Advanced Intelligent Systems.
Md. Ataur Rahman et al. Artificial Somatosensors: Feedback Receptors for Electronic Skins. Advanced Intelligent Systems, published online September 1, 2020 doi: 10.1002/aisy.202000094
Peter J. Turnbaugh, Ruth E. Ley and Jeffrey I. Gordon are at the Center for Genome Sciences, Washington University School of Medicine, St Louis, Missouri 63108, USA.
Peter J. Turnbaugh, Ruth E. Ley & Jeffrey I. Gordon
Micah Hamady is at the Department of Computer Science, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
Claire M. Fraser-Liggett is at the Institute of Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Rob Knight is at the Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA.