From Sun Worship to Space Travel: A Brief History of Light Therapy

Light has always been revered. Long before wavelengths could be measured, people recognised that sunlight sustained life. Ancient Egyptian, Greek and Indian cultures associated the sun with health, energy and renewal, and natural sunlight was used in early forms of heliotherapy. Here’s a brief look at how that instinct evolved into the precisely controlled light therapy, known as photobiomodulation (PBM), that &RECOVER is built on.

Ancient reverence for the sun

In India, Surya, the sun, was honoured as a source of life and vitality. Today’s Sun Salutation, or Surya Namaskar, continues this symbolic relationship between light, movement and wellbeing, although the familiar sequence of yoga postures developed much later.

Florence Nightingale: light and recovery

During the nineteenth century, Florence Nightingale recognised that a patient’s surroundings could influence recovery. Her approach combined fresh air, cleanliness, nutrition, quiet and access to daylight.

In her 1859 book Notes on Nursing, Nightingale wrote that, second only to fresh air, sick people needed light - and particularly direct sunlight. She believed that dark rooms could be harmful and that the effects of light extended beyond simply improving a patient’s mood.

‘Second only to their need of fresh air is their need of light.’

Nightingale was recording observations from nursing practice rather than conducting a modern clinical trial. Nevertheless, her insistence on bright, naturally lit hospital rooms helped establish daylight as an important part of a supportive healing environment.

Niels Finsen: light becomes medicine

Toward the end of the nineteenth century, Danish physician Niels Ryberg Finsen began investigating the biological effects of concentrated light.

Finsen used ultraviolet radiation to treat lupus vulgaris, a serious form of skin tuberculosis. In 1903, he received the Nobel Prize in Physiology or Medicine for his contribution to treating disease with concentrated light radiation.

Finsen’s treatment was not modern red-light therapy or photobiomodulation. It used ultraviolet light, which behaves very differently. However, his work demonstrated that particular parts of the light spectrum could produce particular biological effects.

Endre Mester: an unexpected discovery

Modern photobiomodulation began with an unexpected observation.

In 1967, Professor Endre Mester, a Hungarian physician and researcher at Semmelweis University in Budapest, was investigating the biological effects of the newly developed laser.

Mester shaved areas on the backs of mice and exposed one group to a low-intensity ruby laser emitting red light at approximately 694 nanometres. He was studying whether repeated laser exposure might damage the skin. Instead, he observed that hair grew back faster in the treated mice than in the untreated control group.

He also found that increasing the exposure did not necessarily increase the effect. This provided an early indication of an important principle in photobiomodulation: more light is not always better.

Mester called the effect ‘laser biostimulation’ and subsequently investigated low-intensity laser light for wound healing and difficult-to-heal skin ulcers. His work helped establish the field later known as low-level laser therapy and now more commonly called photobiomodulation, or PBM.

The original hair-growth experiment was conducted in mice, so it was not by itself evidence for treating human hair loss. However, it opened an important new field of research.

NASA: from growing plants to supporting tissue

Almost three decades later, NASA helped advance light therapy in a different direction.

During the 1990s, NASA-supported researchers developed powerful, energy-efficient LED arrays for growing plants and food during space missions. LEDs were particularly useful because they could produce selected wavelengths while consuming relatively little power and generating less heat than conventional lamps.

After red LEDs proved practical for plant growth, NASA’s Marshall Space Flight Center supported research into their possible medical applications. This was relevant to long-duration spaceflight, where reduced gravity can contribute to muscle and bone loss and may interfere with normal tissue repair.

Researchers led by Dr Harry Whelan studied red and near-infrared LEDs in skin, bone and skeletal-muscle cells, as well as in experimental wound-healing models. This work helped demonstrate that photobiomodulation was not limited to narrowly focused lasers. LEDs could deliver selected wavelengths over a wider area, supporting the later development of panels, wraps and mats.

NASA did not discover photobiomodulation - the foundations had already been established by Mester - but its research helped develop practical LED technology and expanded scientific interest in light and tissue recovery.

Light therapy today

Modern photobiomodulation uses controlled, non-ionising red and near-infrared light. It is not the same as sunbathing, ultraviolet treatment or heat therapy.

Its effects depend upon the wavelength, intensity, treatment time, distance from the skin and total dose delivered. Different devices also serve different purposes: panels and mats provide broad exposure, while handheld lasers allow more targeted application to particular muscles, joints and tendons.

From ancient sunlight rituals to Florence Nightingale’s hospital wards, Finsen’s pioneering phototherapy, Mester’s ruby laser and NASA’s space programme, our understanding of light has changed dramatically.

Light does more than illuminate our surroundings - it interacts with life.

Sources

Florence Nightingale, Notes on Nursing (1859): gutenberg.org/ebooks/17366

The Nobel Prize in Physiology or Medicine 1903 - Niels Ryberg Finsen: nobelprize.org/prizes/medicine/1903/finsen/facts/

Mester E., Szende B., Gartner P. The effect of laser beams on the growth of hair in mice: PubMed 5732466

NASA Spinoff, Lighting the Way for Quicker, Safer Healing: spinoff.nasa.gov/Spinoff2005/hm_1.html

Whelan H.T. et al. Effect of NASA light-emitting diode irradiation on wound healing: PubMed 11776448