The basics of photomedicine, part 1

Author: Milan Rajković, PhD

Table of Contents

If you are reading this text it is likely that you are already familiar with the most important features of our product.


light, nature, photons, electromagnetic waves, photomedicine

Namely, Lucha t8 is related, although not solely, to the effects of light on the human body. Light is characterized by its wavelength and its frequency, however in the Lucha t8 device the added feature is the light pulsation at regular intervals at the Schumann frequency of 7.83 Hz. The science behind Lucha t8 and its health effects, as well as information on related issues from various scientific disciplines, health and medicine will be presented from in a series of articles. We start with a short introduction to light.


Light represents an electromagnetic radiation, a form of energy that travels through space. Although there are many other forms of electromagnetic radiation, such as the one in microwave ovens, TV sets, X-rays etc., they all share the common property that they exhibit wavelike properties. Waves are disturbances of the medium through which they propagate, such as air, and they are characterized by their amplitude, wavelength and frequency. The characteristic feature of electromagnetic waves is that they consist of electric and magnetic waves oscillating perpendicular to one another. Visually, it looks like this:


Figure 1 Electromagnetic wave consisting of electric and magnetic fields

Basic quantitative properties of waves are amplitude, wavelength and frequency. The amplitude is the distance between the level of the central axis and the highest point on the crest of the wave, and the wavelength is the distance between two consecutive crest peaks. The frequency is the number of wavelengths that pass by a reference point in space every second. The unit of frequency is Herz (denoted by Hz) and it is equivalent to “per second” (or 1/s). It is not difficult to realize that wavelength and frequency are inversely proportional, namely, the longer the wavelength the lower the frequency, and vice versa.

The electromagnetic spectrum

Light is not the only form of electromagnetic phenomenon that propagates through space. Microwaves that are generated in the microwave oven are another example. X-rays, Gamma-rays, radio waves, etc are some more phenomena that represent electromagnetic radiation. All electromagnetic waves can be classified according to their various wavelengths (equivalently according to frequencies) as illustrated in Fig. 2.


Figure 2 The electromagnetic spectrum. Image from UC Davis ChemWiki, CC-BY-NC-SA 3.0. UV denotes ultraviolet waves, IR infrared waves. Humans can see waves in the very narrow region of the spectrum (approximately 400-700nanometers).

You may have noticed that the Schumann frequency of 7.83 Hz is on the very end (right hand side) of this spectrum. To the right of the visible spectrum are waves that have low energy and thus, are not harmful. This is a general property of electromagnetic radiation, namely that waves lower in frequency have lower energy, and vice versa, waves higher in frequency have higher energies. These waves are constantly around us, such as radio waves. For example IR (infrared) radiation represents heat waves radiating from the hot bodies. Radiation on the left side of the visible spectrum, ultraviolet (UV) radiation, X-rays and gamma-rays have large energies and can induce harmful effects on humans.

UV radiation can be also damaging to human health so the reason for advocating the use of suntan lotion when being exposed to the sun rays. X-rays are also high in energy and could induce harmful effects. When used for medical purposes the exposure is very limited in time and only the area of the body being imaged is exposed to the penetrating X-rays, while the rest of the body is well shielded. Gamma rays are particularly damaging due to their very high energy. Their origin can be from the nuclear materials, but also from outer space, however due to the absorbing power of earth’s atmosphere, they do not reach the surface of the earth. In the next section we explain where the relationship of frequency and energy comes from.

The dual nature of light and the photon

One of the great discoveries of the 20th century was that the energy of the electromagnetic radiation is quantized so that it can be transmitted in packets of particular size. Each packet is known as a quantum of energy, also known as the photon. Thus, the light can behave both like a wave and like a particle, i.e. it has dual nature. The photon carries energy which is directly proportional to its frequency.

The basics of photomedicine

Although Lucha t8 is not intended to be a medical device, in the sense that it could be used for treatment of a disease of any kind, it is instructive to get familiar with some basic facts about photomedicine as there are some overlapping concepts and ideas.

Photomedicine is the area of medicine which uses the knowledge of the effects of light on the understanding of health and disease. It is based on photobiology which is the area of science which is concerned with the interaction of nonionizing electromagnetic radiation with biomolecules and the resulting biological responses. Only absorbed light can lead to photochemical reaction in the body tissue and only radiation in the ultraviolet (200-400 nm, nanometers) and visible wavelengths is capable of initiating chemical processes in the human body. Human body is constantly exposed to the influence of the ultraviolet (UV) radiation from the sun, which, as mentioned earlier, may be dangerous for human beings due to the large energy of these waves. These negative effects such as erythema, skin ageing and skin cancer may occur due to the exposure to the UV waves.

On the other hand, UV radiation induces production of previtamin D3 in the skin and thus enables synthesis of the important vitamin for humans, namely D3. Thus, the skin, being an interface between human body and the environment acts as a sun screen, enabling life-preserving processes to initiate beneath the skin’s surface. Skin is also exposed to the influence of visible and infrared radiation from various sources including interior lighting, phototherapy devices and systems, manmade heat sources, etc. Photomedicine includes both the study and treatment of diseases caused by exposure to different types of light and the diagnostic and therapeutic applications of light for curing a disease, or relief of pain and inflammation and restoration of proper functioning of internal organs. However, applications of photomedicine are not restricted to the treatment of ailments but also for improving the general well-being of the users and in the course of its use may provide short and long term health benefits.

Responses of skin to light started by the absorption of radiation, including ultraviolet, infrared and visible light, by molecules in skin. As a consequence, the photo activated molecules are converted into new chemical entities (photoproducts) that cause a series of biochemical changes. These include, among others, induction of enzymes, secretion of cytokines, and repair of damaged tissue structures. The effects on skin surface and tissue structure may be monitored and subsequently observed after a certain period of time. It should be emphasized that the responses of skin to light are strongly dependent on the color, or wavelength, of light used. Each wavelength induces different response in the molecules below the skin’s surface. Not all wavelengths have the same effects; in fact, specific wavelength ranges are responsible for specific responses.

There are two important reasons why the wavelength of light is important in photomedicine. First, it determines the depth to which the light energy penetrates into skin, and, second, each of the types of molecules in skin absorb specific wavelengths. Of course, the magnitude of skin’s response depends on the amount of incident light and on the amount of absorbed light. The magnitude of the response does not depend on the rate at which the light energy is incident or absorbed. In order for the light to cause an effect in skin, and in the tissue below the skin’s surface, it has to be absorbed by biomolecules and initiate chemical reactions in the tissue. The light absorbing molecules are referred to as chromophores. In the process of light absorption, the electromagnetic energy of the photon is converted into chemical energy of the molecule, more precisely into the chemical bonding energy of the molecule. The surplus of energy contained in the molecule can transform chemically to form photochemistry products, emit light or generate heat.

From the aspect of photomedicine, the most important feature is the creation of photochemistry products, because photochemistry reactions of biological molecules initiate skin response to light. The molecular structure of chemical compounds found beneath the skin surface determine which wavelengths of light radiation (including UV and infrared), the compounds can absorb. Human skin contains many chromophores absorbing radiation in the visile, infrared and ultraviolet wavelength range, but not all of them initiate response to the absorbed radiation. The most important chromophore for photobiological responses in the UV range (particularly UVB range) is the DNA. Some amino acids, specifically triptophane, responsible for the generation of melatonin, usually do not trigger biological response with respect to the incident light. Nevertheless, they have an important role in removing the large amount of the UVB radiation before it reaches the DNA in cells.

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