Light, consisting of photons of energy, can be absorbed by physical matter like molecules and cells. Once absorbed, it creates a chemical reaction and changes the target matter in some way. The study of this reaction, and understanding what wavelengths have a desired (or undesirable) effect on matter, makes up photochemistry.
Photochemical reactions happen on many levels, and understanding them is key to developing new products and medical treatments. When light is absorbed, it can cause the skin to create Vitamin D, or it can cause medications and plastics to degrade.
The central principle in photochemistry, first stated by Grotthuss and Draper in 1818, is that only absorbed light can produce a chemical change.
The science of PhotoChemistry, 2nd Ed. pg47, KenDric Smith, 1989.
The most commonly known form of photochemistry is photosynthesis, where plants are able to convert carbon dioxide into organic compounds and sugars once the plant is exposed to light. But photosynthesis is most efficient only when exposed to certain wavelengths of light. Conventional wisdom once held it was white light, or mid-spectrum light, that spurred plant growth. However, further research demonstrated far red, near infrared light did the bulk of the work. That photochemical discovery led to the development of a lower-power, but highly effective way to grow plants in space.
Learn more about photobiomodulation, using light to affect change in human cells.
Light waves can also affect animal and human cells in a similar way to plants. This phenomenon is called photobiomodulation, and is essentially using the power of light waves, at just the right wave length, to positively affect cells.
This website is intended for healthcare professionals and clinical researchers only. All of the treatments using LED phototherapy devices that are discussed on this website are in various stages of investigation and have not been approved by the FDA except where specifically stated.