The field of medicine is split into various specialties including photomedicine. This area covers those procedures, treatments and conditions that have light and light energy as a central feature. Although this can include established concepts as sunscreen and vitamin D production, the newer potential applications for light energy include tissue regeneration and research into cancer treatments.
Light is a form of energy transmission, and sunlight is a very important source of energy for living things. Plants can harness energy and help turn it into growth, and animals can also use light for biological purposes. An example of this is Vitamin D production in humans, which only occurs when the skin is exposed to sunlight. Humans also use light patterns and intensities as signals to wake up and go to sleep. Seasonal Affective Disorder (SAD), for example, is a depressive condition that is treatable through light therapy during the winter months, when it is most common.
As well as natural light treatments and procedures that provide natural light intensity to alleviate conditions such as these, photomedicine also covers light energy of different intensities and types. Lasers are one example of this, and the energy of some lasers is so high that they can destroy cells. As of 2011, research is ongoing into the potential for lasers to selectively kill off cancer cells. Lasers of lower energy can also stimulate new cell turnover, giving photomedicine applications in the treatment of skin conditions, and also is the cosmetic arena of renewing skin and making people look younger.
Medical imaging is an important part of photomedicine, as various wavelengths of light energy can be used to pass through tissues and give a picture of the body with regard to the density of the individual tissues. As well as general medicine, these techniques can also find applications in dentistry and in optometry. Substances called photosensitizers, which are administered to the patient, and which give out a recognizable light signature under the right situations, can also help to identify diseased tissues in a medical imaging system.
Some medical conditions arise because of light exposure, which is another sector of photomedicine. Skin cancer is one example of a disease caused by light, and sunscreen is a preventative measure for this condition. Photosensitivity is another type of problem, which can occur as a side effect of certain medicines, or as part of the symptoms of a more serious condition that can prevent the affected person from going out under the sun entirely.