Light therapy began in ancient Egypt, Greece and Rome, when those afflicted by sickness were brought out into sunlight during the day. This was thought to aid in curing their wounds or illnesses. Soon these ancient cultures began to place coloured fabric screens under which people with various diseases could sit. The truth is that we are surrounded by light all the time. It is our method of seeing what is around us. Just like bats can see by bouncing sound off objects and back to their ears, we see by detecting light reflected off our surroundings. Light travels to objects and bounces off them, our eyes then pick up they reflected rays and we "see" the physical world surrounding us. Of coarse this excludes all objects which do not reflect light in one way or another, such as magnetic fields. These objects we cannot see, at least not with our eyes.

Light is one of the most basic constituents of life. If the sun ceased to shine, in due time most of the life on our planet would die out. The plant species in our world absorb light energy directly and use it to create organic fuel (glucose) and oxygen from carbon dioxide and water. Without sunlight plants would die out, and along with them every organism which depends on plants for food (which is the majority of organisms).

Just as the pigment chlorophyll utilizes sunlight for purposes which serve the plant, humans also have mechanisms which would grind to a halt if sunlight suddenly became absent. An example of one of these systems is the circadian sleep cycle. This cycle controls when the body should feel awake and when it should feel sleepy. This cycle is in turn controlled by the amount of light coming in through the eyes at any one time during a 24 hour period. If a person is placed into complete darkness for a few days, this rhythm gets disrupted and the production of a very important hormone called melatonin is impaired since there is no light. This results in a slow down of the body's metabolism and mood changes will also occur (eg. depression). Babies who are born with jaundice are treated with blue light. This helps in the breakdown of the excess bilirubin which accumulates through a process called photo-oxidation. These examples are only a few out of an ocean of facts about why light is important in our everyday lives, and also why it can be of a healing nature. In both of these cases light can assist with the disorder. Many other disorders are also based on simply light deficiencies.

We must also consider what else constitutes our body - some form of still undefined energy. Without this energy the body would not live, as a device would be non-functional without electricity. If our electricity suddenly ceased to course through our nerves, we would also stop functioning. Light is a form of energy, thus by supplying our bodies with more energy we can function more optimally. Most people tend to sleep much better when they have spent a day outside in the sun. This at its very core is a form of light therapy.