Humanity has long recognized the healing power of sunlight, integrating it into cultural and medical practices worldwide. This article traces the fascinating journey of light therapy through the ages.

1. Ancient Light Therapy: From Sun Worship to Medical Practices

Ancient Egypt’s Sunlight Applications

Around 1300 BCE, Egyptian Pharaoh Akhenaten acknowledged sunlight's life-giving qualities. Historical records show ancient Egyptians treated chronic ulcers by exposing affected areas to sunlight. Similarly, sunbathing was a common health practice across ancient Egypt, Babylon, Mesopotamia, Greece, and Rome. In many parts of Africa, sun worship and belief in its healing powers remain deeply ingrained cultural traditions.

Illustration: A mural of Akhenaten’s family basking in sunlight reflects the ancient Egyptians' reverence for the sun and belief in its healing powers.

Greek and Indian Philosophies of Light Therapy

The term "heliotherapy," derived from Helios, the Greek god of the sun, means sunlight therapy. Around 400 BCE, Greek physician Hippocrates noted that sunlit mountain slopes fostered health, recommending sunbathing as a treatment for physical and mental ailments. Sunlight therapy was also provided to Olympic athletes to enhance their performance.

In India, Ayurvedic medicine combined sunlight with photosensitive herbs, such as psoralen, to treat conditions like vitiligo as early as 1400 BCE.

Light Therapy in Chinese Traditions

Ancient Chinese texts also highlight the importance of sunlight. The Huangdi Neijing advised abundant sunlight during summer and sunlight exposure in winter for better health. Tang Dynasty physician Sun Simiao emphasized sunlight's preventive role in diseases. Chinese feng shui theories also associated well-lit homes with physical and mental well-being.

2. The Middle Ages: The Decline of Light Therapy

During the Middle Ages, light therapy fell into disuse. Pale skin became associated with beauty and status, while darker skin was stigmatized. As Christianity gained influence, its emphasis on the soul over the body led to restrictions on physical exposure to sunlight. Practices such as sun worship and sunlight-based treatments were dismissed as pagan and often condemned. Sunbathing itself was even labeled as sinful. These cultural and religious shifts relegated light therapy to the margins of medical practice.

3. The Renaissance of Light Therapy: A Scientific Revival

In the 19th century, the pioneers of modern sunlight therapy were not doctors but Austrian researcher Arnold and French scientist Ponton, who conducted systematic studies of sunlight therapy in sunlight sanatoriums. In 1815, Corbin highlighted its effectiveness in treating conditions such as rickets, scurvy, rheumatism, paralysis, and swelling. By 1816, Deberle analyzed the effects of sunlight by separating it into infrared and visible light.

During the Crimean War, Florence Nightingale noticed that exposing wounded soldiers to sunlight significantly improved their recovery. Upon returning to Britain in 1858, she advocated for better lighting in hospitals and famously stated, “Direct sunlight is essential for recovery.”

In 1893, Niels Finsen demonstrated the therapeutic effects of specific wavelengths of light. He found that ultraviolet light effectively killed bacteria, while infrared light aided smallpox recovery and prevented scarring. His work with ultraviolet light to treat lupus earned him the 1903 Nobel Prize in Physiology or Medicine, establishing him as the “Father of Light Therapy.”

Dr.Finsen

London Hospital uses Finsen lamps to treat lupus.

4. Modern Light Therapy: From Tradition to Innovation

Since the 1960s, advances in lasers and LEDs have driven innovation in light therapy. Photobiomodulation (PBM) emerged as a key modern technique, using specific wavelengths to activate biological processes without heat or toxicity. PBM has proven effective in wound healing, tissue regeneration, and alleviating pain and inflammation.

Research also highlights the therapeutic benefits of red and near-infrared light, particularly for respiratory diseases, including complications from COVID-19.

In 2020, research by Alfredsson and colleagues highlighted that sunlight deficiency is linked to approximately 340,000 deaths annually in the U.S. and 480,000 in Europe. It is also closely associated with the high prevalence of various diseases. This finding has drawn greater attention to the role of sunlight in health, emphasizing that regular, safe sunbathing—avoiding sunburn—can help people of all skin tones maximize the health benefits of sunlight while reducing risks, including melanoma.

The history of light therapy demonstrates that the healing power of sunlight has never truly been forgotten. Integrating sunlight and therapeutic light sources into modern healthcare presents a promising direction for future medical and wellness advancements.