It's just light, isn't it?
With all the ridiculous things we see and hear from supposed "experts" on the internet, it is not surprising that many of us have become skeptical about a great many things. When you hear that certain frequencies of light can be helpful for treating certain skin conditions it's probably sensible if a red flag pops up and makes you question if it's true.
Science & Light
Ever since the prism was invented, scientists have investigated the properties of the components of light. One clever scientist, Sir Frederick William Herschel (1738-1822), decided to measure the temperature of the light split from a prism. Violet was the coldest, but as he moved along from blue to green to red, it got hotter and hotter. As a control, he also put a thermometer in the region beyond red and found this to be the hottest zone of all. He had discovered Infrared (meaning "below red") light.
A year later, Johann Wilhelm Ritter read about the experiment and wondered if there was invisible light above violet. He devised a test and found that there was indeed invisible light there, which was named Ultraviolet (above violet).
Scientists are naturally curious people. Present them with a mystery and they will do their best to figure it out. So, with all these different "kinds" of light, did one color do anything special that another color wouldn't do? Apparently they did.
Medically Purposed Light
Early experiments, before we had artificial illumination, were reliant on ordinary sunlight. Diseases, like rickets in children, occurred because of a lack of vitamin D in the diet. It was exacerbated in colder climates where lots of heavy clothes were worn and sunlight exposure was minimal. This prevented the skin from manufacturing the missing vitamin D.
It is the same in elderly populations, too. Vitamin D helps the body use calcium properly to keep bones strong, so while children were getting bow-legs from weakened bones, elders were getting osteoporosis where spines would curve and bend as they aged. Other bones became much more prone to fracturing, too.
In these cases, scientists observed that those getting enough sunlight exposure avoided these diseases. They didn't understand the process, but it was a mystery worth solving.
Nils Finsen [1860-1904], was a Faroese-Danish scientist, who was interested in how plants and animals sought sunlight. At age 23, he became afflicted with a disease that was unknown, and not identified until 10 years after his death, as Niemann-Pick disease, in 1914.
His personal trials led him to experiment upon himself to see if light would provide an effective treatment. He invented the carbon arc light (later known as the Finsen Light) as part of his experiments. Although he began with glass lenses, he switched to a quartz lens as this allowed the copious production of UV light, but was sufficiently diffuse to avoid burning the skin.
He was among the first to recognize the bactericidal properties of UV light—its ability to kill these life forms—and to create a sterile surface or work area. He investigated the amount of light that could be tolerated before erythema arose (reddening due to increased blood flow). Having observed that his light had positive effects on smallpox scars in 1893, he sought to enhance his experiments.
In 1895, his first real patient came from the local electrical light works company where Finsen was conducting his experiments. The man had tuberculosis of the skin, with significant and painful skin lesions. Finsen's eponymously named light was well on its way to curing the problem in just four days of treatment where many previous interventions had accomplished nothing. Skin Phototherapy was thus born as an infant science, destined to grow.
Post-World War II Disillusionment
After 1945, the medical profession moved away from bathing people in colored light. They suggested the effect was more psychological than physical.
The light sources of the time were too hot to be brought close enough to the skin without doing damage. Now that virtually heatless LEDs have arrived, the extremely well-controlled frequencies (down to just a few nanometers) can be targeted to specific areas for significant effect while avoiding most damage.
UV light is quite effective for treating many skin conditions. It is normally classed as UVA, UVB, or UVC, depending on its frequency.
Psoriasis is an autoimmune disease where the body sometimes misidentifies parts of itself as foreign material and attacks it. Medicinal techniques, such as coal tar or anthralin-salicylic acid, can significantly decrease symptoms, by slowing skin-cell growth. Psoriasis can lead to Psoriatic Arthritis, where joints become involved including distorted bone growth. If psoriasis is treated early enough with modern interventions, often the arthritic portion can be completely avoided.
In aggressive cases, a dermatologist may specifically recommend UVB therapy, three times per week for 2-3 months. UV light also help to retard skin cell replacement and decrease symptoms of scaling and flaking.
Vitiligo, a depigmentation disease of the skin, can have severe psychosocial impacts on patients, particularly those with dark skin tones because of the vivid contrast between the two colors. Laser therapy utilizing a 308 nm Excimer Laser can restore a majority of the normal color in as little as 12 weeks of treatment. This has a pronounced effect on personal confidence and social acceptance.
Atopic Dermatitis (Atopy: allergies caused by an exaggerated IgE-mediated immune response to ordinary substances), often referred to as eczema, is also responsive to phototherapy. Specialists use many different techniques with varying degrees of effect. This is one a one-size-fits-all solution, such that sometimes it requires just natural sunlight, but could require either narrow or broad band UVB exposure. It might require UVA alone, or in combination with UVB to get results. In other cases it can call for full-spectrum light with added UVA and Infrared…
Phototherapy is even effective for chronic pruritus (itching) irrespective of cause, and in elderly patients with chronic idiopathic pruritus, is often the only effective treatment.
Red vs. Blue
Frequencies of 415 nm (blue), 633 nm (red), and 830 nm (infrared) were the subject of an NIH article PMC5843358, by Glynis Ablon, MD, FAAD. It mentions efficacy treating psoriasis (as discussed earlier), enhanced wound healing (reducing healing time by half, after skin ablation treatment), both squamous cell and basal cell carcinomas, acne vulgaris (caused by a particular bacteria sensitive to blue light), as well as actinic keratosis, and some cosmetic procedures, such as treating rosacea, which were quite effective.
Light-based treatments can have dramatic effects on the skin.
Interestingly, Squamous cell carcinomas had much better results with Photodynamic therapy (PDT). Cryogenic treatments were less effective and cured 10/20 lesions in one treatment, plus 2-3 more treatments for the remaining 10. PDT cured 15 in the first session, and the remaining 5 in the second. The best part, however, is that, unlike cryogenics, there were no ulcerations (5 for cryo) or infections (2 for cryo) when using PDT instead.
Basal cell carcinomas were less responsive due to recurrence. A second test, involving following the first treatment with a second just seven days later had very good results of 100% response after one month.
The light itself is non-thermic, and has few if any aftereffects. The most common photosensitizer used is ALA (5-aminolevulinic acid). When using some of the creams, lotions, or medications, they can cause erythema (reddening), scaling, or even scabbing. These effects generally only last 3-14 days, and the results are considered, by most patients, to be worth the trade-off.
Is Phototherapy Real?
Returning to our original question then, yes, it is real, and yes, it is effective. Faced with such tiny light sources, it does require some substantiation to confirm that there is an effect. Modern people are becoming quite familiar with LED light sources and their versatility.
How We Got Here
Originally it was a tiny epoxy bulb with (if you looked closely enough) a couple of oddly shaped pieces of shiny metal inside that somehow produced light. In the beginning we could only produce red and green light, but through some trickery, we managed to make it produce orangey-yellow light, too.
Light Emitting Diode (LED)
Blue eluded us for years until three scientists (Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura) finally managed to create the blue LED, for which they won the Nobel Prize in Physics.
Shuji Nakamura, Isamu Akasaki, and Hiroshi Amano
For more than a century we've generated much of our light by running a significant amount of current through a temperature-resistant metal filament inside a vacuum. Sadly, up to 95% of that current was wasted because that filament had to reach a temperature of over 2,500º Celsius (4,600º F) in order to create "white-enough" light to be considered useful. The bulb's glass envelope would reach scorching temperatures exceeding 65-125º C (150-250º F), capable of burning human flesh.
To get other colors of light we had to use physical filters made of colored glass or "gels" to remove all the undesired frequencies. This just wasted more energy being absorbed by the filter.
Alternatively, we could use more esoteric methods, such as plasmas-discharge tubes with trapped gases such as neon, radon, krypton, xenon, mercury, and helium, all falling under the heading "neon-lighting". Now we could produce a whole rainbow of colors, and they used far less energy than ever before. You might be familiar with the city of Las Vegas that really took this discovery to heart!
Despite our best efforts, until our three Nobel Prize Laureates performed their miracle, here was no chance of getting to where we are today with Photodynamic therapy. And, in point of fact, your most precious device, your smartphone, or your tablet, or you laptop would still be heavy, power-sucking monsters, an televisions would be cathode ray tubes giants. So, one more time… Let's hear it for Science!
- Nakamura M, Koo JYM. Phototherapy for the treatment of prurigo nodularis: a review. Dermatol Online J. (2016) 22:5. Available online at: https://escholarship.org/uc/item/4b07778z
- Oetjen LK, Mack MR, Feng J, Whelan TM, Niu H, Guo CJ, et al. . Sensory neurons co-opt classical immune signaling pathways to mediate chronic itch. Cell (2017) 171:217–28. 10.1016/j.cell.2017.08.006