The history of light therapy dates back more than 3000 years ago, in India; where sunlight was used for therapeutic purposes. It was even recorded in the sacred Hindu texts. In today’s world, the beneficial effects of light therapy are well-established. They involve the use of visible light or non-visible ultraviolet light to treat countless health conditions.

Light therapy boxes that emanate full-spectrum light similar in composition to sunlight are often employed. Identifying the individual circadian rhythm and selection of proper timing is critical for adequate administration of light therapy.

Most of the sun’s energy (radiation) is harmful to us. It is often blocked by our atmosphere, however, some of this tremendous energy still reaches earth, and we call the visible portion of this energy “light.”

Given how our sleep patterns have been governed by a 24-hour day-night cycle, it, therefore, means that our sleep cycles are regulated by a biological clock, otherwise known as circadian rhythm, which works as an automatic responder for the brain. It alerts our body when it is time to stay awake (day) and when it is time to fall asleep(night).

Color is Light Energy

The wavelengths of visible light are tiny and ranges from 400 to 700 billionths of a meter, or nm. Natural daylight contains within it each color of the rainbow that can be defined by a range of tiny wavelengths as seen below:

Color – Wavelength

Violet Light – 380-450 nm
Blue Light – 450-495 nm
Green Light – 495-570 nm
Yellow Light – 570-590 nm
Orange Light – 590-620 nm
Red Light – 620-750 nm
Infrared energy (non-visible) – 750 nm – 100 µm

The Rationale Behind Light Therapy

Two properties define the biologic grounds of light therapy (phototherapy). those two are wavelength and intensity. The wavelength range of visible light is roughly from 780 nm (red end) to 400 nm (violet end). The circadian rhythm is often seen as the body clock and it represents a 24-hour cycle that regulates sleep and other physiological processes.

Researchers most often utilized bright white light in order to study light effects on human circadian rhythm in the past, but recent studies have demonstrated the better effectiveness of short wavelength blue light with better phase shifting properties when compared to the rest of the visible light spectrum.

Light therapy targets the subjective human biologic clock and attempts to reset the phase of the clock’s activity, relational to the cycles of light and dark. Thus, the common goals of this type of therapy are to synchronize the sleep-wake cycle with the subjective night, to facilitate sleep at the desired time of day or night, and to accomplish indirect effects on the mood of a patient.

How Does it Work?

Light therapy uses artificial light to imitate the exact lighting conditions we normally receive during the daytime. By exposing our eyes to artificial sunlight,  this therapy resets our circadian clock at any time of the day (or night) and in the process adjust our 24-hour biological clock to a more consistent sleep schedule.

Light therapy is also widely used in treating the seasonal affective disorder, which is a form of depression caused by the lack of light during winter. By utilizing artificial light, light therapy compensates for the light deprivation and helps the person afflicted with the disorder to shake off the winter-related health issue.

Light Therapy Treatment Techniques

There two general ways that light therapy treatments are administered. These are: Light taken through the eyes, and Light shone on the skin. Light travels through the eyes directly into the hypothalamus of the brain and has an effect on every system of the body. Bright light therapy treatments use a “lightbox” that uses white or blue light to provide intense exposure under controlled conditions.

Benefits are quite widespread and include the prevention of seasonal affective disorder (SAD) and minimizing its symptoms, improving circadian rhythms in order to promote better sleep, and many other benefits. Treatment is as simple as sitting near a lightbox, which is turned on, with your eyes open.

It is not recommended that you stare directly at the light, so you can simply orient yourself toward it while you conduct your daily activities such as reading, and eating your meals.

Dawn Simulators

Dawn simulators are a light therapy that is usually utilized, to help in the treatment of the seasonal affective disorder (SAD). They are also used by some individuals who wish to wake up naturally and build a kind of an “alarm clock” into their bodies.

A standard dawn simulator treatment involves timing the devices to start to add light to a bedroom so that it gradually increases over time (say, a period of thirty minutes to two hours) before it is time to rise.

Dawn simulators usually use an illuminance range of 100 to 300 lux, and some people with SAD find that this helps them to feel as though they have experienced more daylight throughout the winter periods.

Some Medical Uses of Light Therapy

Phototherapy is a light therapy technique that uses reactive photosensitizing agents that kill cancer cells when exposed to a certain kind of light. Thus, by using reactive compounds that are activated by certain kinds of light, photodynamic therapy has created an alternative cancer treatment that is non-invasive and efficient.

Similarly, Low-intensity Light Therapy as a technique in light therapy has a wider range of medical applications, which is known to provide an effective treatment for wounds, arthritis, acute stroke, recurrent herpes, and a host of muscular and skeletal chronic conditions. Low-Intensity Light Therapy has been recommended by experts and has been the preferred method by many due to its non-invasive nature.

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