The Ultimate Guide to Red Light Therapy: Revised and Updated

The Ultimate Guide to Red Light Therapy: Revised and Updated

Chapter One

A History of Red and Near-Infrared Light Therapy

Throughout human civilization, light has been revered not just as a source of illumination, but as a profound healer. Ancient civilizations across the globe recognized the sun as sacred—a life-giving force worthy of worship and reverence. From the solar deities of Egypt to the sun-honoring rituals of indigenous cultures in the Americas, our ancestors intuitively grasped the sun’s vital role in health and healing. Though they lacked our modern scientific understanding of the precise physiological and biochemical mechanisms, they recognized a fundamental truth about light’s relationship to living things—an insight that led to healing traditions that modern science is now validating and explaining at the molecular level.

The therapeutic use of light—what we now call “photomedicine” or “photobiomodulation” (PBM)—has documented roots stretching back over three millennia. In India, the ancient Hindu text Atharva Veda, written around 1400 BCE, contains some of the earliest written references to healing practices involving sunlight. These weren’t just spiritual rituals but systematic approaches to treating various ailments through controlled light exposure.

As remarkable as these ancient practices are, some researchers propose that our relationship with healing light may extend millions of years farther into our evolutionary past. Iain Mathewson proposed this intriguing hypothesis in his paper “Did human hairlessness allow natural photobiomodulation 2 million years ago and enable photobiomodulation therapy today? This can explain the rapid expansion of our genus’s brain.”

While scientists had previously attributed human hairlessness to better temperature regulation through sweat glands or increased vitamin D production from UV exposure, Mathewson offered a revolutionary perspective. He argued that “the penetration of red/NIR light into mitochondria-rich muscles could release systemic mediators that stimulated human brain growth over millions of years.” This could potentially explain why the timeline of human hairlessness coincides with our species’ dramatic brain development.

Moving from evolutionary theory to recorded history, humans have been consciously harnessing light’s healing properties for thousands of years.

As civilizations developed across the ancient world, three grand traditions of medicine emerged, each incorporating light therapy in different ways: traditional Chinese medicine, Indian Ayurveda, and ancient Egyptian medicine.

In ancient Egypt, Ra, the sun god, was revered as a source of primal life-giving energy. Ra was depicted as a ram-headed sun god wearing a sun disc and sailing across the heavens in daylight from east to west in a celestial boat. The Pharaoh Amhotep IV of the eighteenth dynasty (1801–1792 BCE) even established a monotheistic religion centered on sun worship. In Heliopolis, a city on the Nile delta, devotees invoked their sun god with fervent and solemn incantations in order to cure illnesses and prevent disease.

The healing power of sunlight was acknowledged even in biblical texts. The Talmud recognized that the sun “carries healing in its wings” (Malachi 3:20). A story tells of Jacob limping due to an accident, and when “the Sun rose upon him,” Rabbi Berachaya interpreted this to mean, “The sun shone upon him in order to heal him.”

In Ayurvedic medicine, sunbathing—called “Atapaseva”—was prescribed for various conditions. As traditional texts explain: “Atapaseva is very useful for lightening the body, increasing the agni and treating bhrajaka pitta. Many conditions can be improved by sitting in the sun; certain types of eczema, psoriasis, arthritis, depression and water retention to name a few. Lying in the sun and meditating upon the solar plexus, is a wonderful shaman for kapha and vata.”

The Greeks and Romans also recognized sunlight’s therapeutic value. Hippocrates taught that “water and sunshine were blended together in the human body to produce the best health.” Romans enjoyed sunbaths in their solaria (called Heliosis), typically followed by cold sponging. The Roman physician Caelius Aurelianus, writing in the fifth century, prescribed sunbaths for a wide range of diseases.

In medieval times, the fascinating “red treatment” became a standard approach to smallpox. The method involved wrapping patients in red cloth, surrounding them with red decor and curtains, and providing only red foods and drinks. John of Gaddesden, a royal physician to Edward I of England who died in 1361, wrote:

. . . Let a scarlet or red cloth be taken and the variolous [pox-ridden] patient be wrapped in it completely—as I did with the son of the most noble king of England when he suffered those diseases . . . I made everything about his bed red . . . it is a good cure and I cured him in the end without the marks of smallpox.

This practice persisted for centuries. Even Queen Elizabeth I was wrapped in a red blanket when she contracted smallpox in 1562, and early modern smallpox wards featured red walls, red curtains, and red lamps—an early example of using specific light wavelengths for therapeutic purposes.

Early Modern Developments

The therapeutic use of sunlight continued into more recent centuries, with reports of light therapy appearing more frequently in medical literature. In 1735, Fiennius described a case in which he cured a cancerous growth on the lip using a sunbath. As long ago as 1774, Faure and other French surgeons reported the cure of leg ulcers through sun exposure. In 1776, LePeyre and LeConte found that “sunlight concentrated through a lens accelerated wound healing and destroyed tumors.”

There were also reports that sunlight had beneficial effects on internal conditions. In 1782, Harris used “sunlight-exposed mollusk shells to improve a case of rickets.” Gauvain in 1815 and Bonnet in 1840 recommended sunlight treatment for chronic joint inflammation. Indeed, in 1845, Bonnet first reported that sunlight could be used to treat tuberculous arthritis (a bacterial infection of the joints).

The scientific understanding of light’s biological effects began to emerge in the early nineteenth century. Two pioneering scientists, Theodor von Grotthuss (1785–1822) and John William Draper (1811–1882), independently discovered what became known as the Grotthuss-Draper first law of photochemistry: “that light must be absorbed by a specific chemical substance in order for a photochemical reaction to take place.” This fundamental principle laid important groundwork for our modern understanding of how light interacts with biological tissues.

The Vitamin D Connection

Theobald Adrian Palm (1848–1928), a physician from Edinburgh, Scotland, who traveled to Japan, made a crucial observation that would eventually lead to our understanding of vitamin D. While in Niigata, he noticed that rickets—a disease then thought to be caused by poverty, poor diet, overcrowded housing, or even poor soil—was remarkably rare among Japanese children, especially those living in sunny climates.

Palm boldly challenged the prevailing theory, noting: “Rickets is a disease of civilization, and is so frequently found in the large cities of America and Europe that it is doubtful whether the children of the poorer classes ever wholly escape it.” He recommended treating children with rickets using sunbaths and relocating them to sunnier regions. His observations eventually contributed to the discovery of vitamin D in 1920, the “sunlight vitamin” that could be synthesized in the skin through UVB exposure.

Leonard Findlay (1878–1947), a pediatrician at Glasgow University, made similar observations and ultimately suggested that rickets was caused by a lack of sunlight, exercise, and fresh air. In his review of rickets etiology, Findlay concluded that:

Rickets is a disease of the temperate zone, being very rare, and, in fact, practically unknown, in tropical and subtropical countries. The staple diet in these climates is anything but nourishing, the people living mainly on rice, or some other cereal, exactly the kind of food which is supposed in this country to generate the disease.

This discovery represented one of the first scientific validations of light’s biological impact on human health. Modern research has vastly expanded our understanding of vitamin D’s role beyond bone health. We now know that vitamin D functions more like a hormone than a traditional vitamin, influencing hundreds of genes and virtually every tissue in the body. Vitamin D receptors are found throughout the cardiovascular system, immune cells, muscles, brain, and endocrine system.