A HISTORY OF HELIOTHERAPY
In 1903, the Nobel prize for Medicine was awarded to a Dane named Niels Finsen. Finsen had invented a focusable carbon-arc torch to treat – and cure – patients with lupus vulgaris, a painful skin infection caused by tuberculosis. While this was the start of the modern medical use of phototherapy, using the sun as a source of healing is much, much older. Older even than the Talmud, which mentions it in today’s daf.
The Nobel Prize in Physiology or Medicine 1903 was awarded to Niels Ryberg Finsen “in recognition of his contribution to the treatment of diseases...with concentrated light radiation, whereby he has opened a new avenue for medical science”.
Perhaps the earliest reference to heliotherapy – that is, using sunlight to heal - is found in Egyptian papyrus records from over 3,500 years ago, which record using the sun, together with ingesting a local weed, to treat skin conditions. The active ingredients of that weed, Ammi majus, were isolated in 1947. These ingredients, together with heliotherapy, were used in the first clinical trials to treat vitiligo, which were conducted, rather fittingly, in Egypt. Further work determined that it was only a narrow part of the sun’s spectrum that was needed to treat vitiligo, psoriasis, and other skin conditions, and so lamps were developed that produced only narrow band ultraviolet light (UVB). These UVB lamps are now a mainstay of treatment for psoriasis.
SUNLIGHT FOR HEALTHY BONES
For most white people, a half-hour in the summer sun in a bathing suit can initiate the release of 50,000 IU (1.25 mg) vitamin D into the circulation within 24 hours of exposure
— Environmental Health Perspectives 2008:116;4. A162
But ultraviolet light – UVB – can also be extremely dangerous. Too much exposure to sunlight will cause skin cancer, as the light produces molecules that directly damage DNA. Here is the great paradox of sunlight – too much of it will burn and can kill – but get the dose right and it is not only curative, but essential for healthy living. Sunlight is needed to produce vitamin D in the skin, and vitamin D is needed to produce healthy bones. Without it, you will develop rickets, a skeletal deformity that is characterized by bowed legs.
Typical presentation of 2 children with rickets. The child in the middle is normal; the children on both sides have severe muscle weakness and bone deformities, including bowed legs (right) and knock knees (left). From Holick M. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr 2004;80(suppl):1678S–88S.
SUNLIGHT FOR A HEALTHY IMMUNE SYSTEM
The sun’s light has been shown to have effect the immune system, although many of these effects are only poorly understood.
When some nerve fibres are exposed to sunlight, they release a chemical called neuropeptide substance P. This chemical seems to produce local immune suppression. Exposure to the ultraviolet wavelengths in sunlight can change the regulation of T cells in the body which can also modulate autoimmune diseases.
SUNLIGHT TO TREAT MELANOMA?
While sunlight can cause skin cancer, it has been shown to release a hormone called alpha melanocyte-stimulating hormone. This hormone appears to limit the damage to DNA damage from sunlight and so may actually reduce the risk of melanoma (but don't try this as a treatment yet. It's certainly not ready for prime time.)
SUNLIGHT FOR YOUR MOOD
Then there’s sunlight for your mood. Seasonal affective disorder – SAD – is caused by a lack of exposure to sunlight, which most affects those living in the northern latitudes in the winter. SAD was first described in 1984 by Norman Rosenthal working at the National Institute of Mental Health but why it happens is still something of a mystery. Rosenthal went on to write several best selling books on SAD and how to beat it. The answer appears to be something to do with sitting in front of a lamp that mimics sunlight (but the evidence that this works is still controversial).
SUNLIGHT FOR BABIES WITH JAUNDICE
Sunlight is also a great treatment for babies with neonatal jaundice. This condition is very common and is caused when the baby breaks down the fetal hemoglobin with which it was born. A product of that breakdown is bilirubin, and if this is allowed to build up in the tissues it can cause lethargy, difficultly feeding, and in rare and extreme cases, brain damage. However, sunlight (or more precisely, the blue band of the spectrum at 459nm) breaks down this dangerous bilirubin molecule into a harmless one called biliverdin. So the best treatment for a newborn baby with mild jaundice is to put them out in the sun. (Failing that, or if the degree of jaundice is not mild, you can consider phototherapy in the hospital.)
The absorbance spectrum of bilirubin bound to human serum albumin (white line) is shown superimposed on the spectrum of visible light. Clearly, blue light is most effective for phototherapy, but because the transmittance of skin increases with increasing wavelength, the best wavelengths to use are probably in the range of 460 to 490 nm. Term and near-term infants should be treated in a bassinet, not an incubator, to allow the light source to be brought to within 10 to 15 cm of the infant (except when halogen or tungsten lights are used), increasing irradiance and efficacy. For intensive phototherapy, an auxiliary light source (fiber-optic pad, light-emitting diode [LED] mattress, or special blue fluorescent tubes) can be placed below the infant or bassinet. If the infant is in an incubator, the light rays should be perpendicular to the surface of the incubator in order to minimize loss of efficacy due to reflectance. From Maisels and McDonagh. Phototherapy for Neonatal Jaundice . New England Journal of Medicine 2008.358;920-928.
The absorbance spectrum of bilirubin bound to human serum albumin (white line) is shown superimposed on the spectrum of visible light. Clearly, blue light is most effective for phototherapy, but because the transmittance of skin increases with increasing wavelength, the best wavelengths to use are probably in the range of 460 to 490 nm. Term and near-term infants should be treated in a bassinet, not an incubator, to allow the light source to be brought to within 10 to 15 cm of the infant (except when halogen or tungsten lights are used), increasing irradiance and efficacy. For intensive phototherapy, an auxiliary light source (fiber-optic pad, light-emitting diode [LED] mattress, or special blue fluorescent tubes) can be placed below the infant or bassinet. If the infant is in an incubator, the light rays should be perpendicular to the surface of the incubator in order to minimize loss of efficacy due to reflectance. From Maisels and McDonagh. Phototherapy for Neonatal Jaundice. New England Journal of Medicine 2008.358;920-928.
SUNLIGHT FOR INFECTIOUS DISEASES
We don't treat infectious diseases with sunlight any more. But it wasn't always that way. Less than eighty years ago sunlight was recommended as a therapy for some patients with tuberculosis. The authors, writing in the journal Diseases of the Chest were cautious:
Even in those cases where the sun can be of great value, it is in no sense a specific cure for any manifestation of tuberculosis. Rest, good food, and fresh air, are still the fundamentals in treating all forms of the disease; and the sun, where it should be used, is only a valuable adjutant...Heliotherapy is not indicated in all cases of tuberculosis. The majority of patients with this disease should never use it...It is not a sure cure for any type of tuberculosis, but is often, especially in some of the extrapulmonary cases, a very valuable—or even necessary—aid.
In today's daf, Abaye noted that the sun can heal, and Rabbi Shimon ben Lakish (a.k.a Resh Lakish) taught that the sun can both reward and punish. Their insights were more correct than they could ever have guessed.
Bright light therapy and the broader realm of chronotherapy remain underappreciated and underutilized, despite their empirical support. Efficacy extends beyond seasonal affective disorder and includes nonseasonal depression and sleep disorders, with emerging evidence for a role in treating attention-deficit/hyperactivity disorder, delirium, and dementia.
— Schwartz and Olds. The Psychiatry of Light. Harvard Review of Psychiatry 2015. 23 (3); 188.
In Egypt around 2000 B.C., the juice of Ammi majus was rubbed on patches of vitiligo after which patients were encouraged to lie in the sun. In the 13th century, vitiligo was treated with a tincture of honey and the powdered seeds of a plant called "aatrillal," which was abundant in the Nile River Valley. The plant has since been identified as A. majus but the trade name Aatrillal is still used today to refer to the yellowish-brown powder made from its seeds.
Ammi majus contains significant amounts of both bergapten and xanthotoxin (also known as methoxsalen), two psoralen derivatives well known for their photosensitizing effects. Indeed, A. majus may well be the world's major source of methoxsalen.
The practice of using Ammi majus to treat vitiligo implicitly acknowledges the hyperpigmentation effects caused by exposure to a photosensitizing agent (such as methoxsalen) followed by ultraviolet radiation. An excess of either the photosensitizing agent or subsequent UV exposure can lead to phytophotodermatitis, a serious skin inflammation. Despite this danger, A. majus is cultivated for its furanocoumarins, which are still used for the treatment of skin disease.
Ammi majus - Wikipedia https://en.wikipedia.org/wiki/Ammi_majus