What is light therapy?
Light therapy is the treatment of a disease, usually a skin disease, using visible or (usually) ultraviolet light.
Dermatology
- UVB is the most used, so with wavelengths between 280 and 310 nm. Since the early 90s, one uses narrow-band; especially the light consists of waves of 311 nm. The exposure is the inflammatory response in the skin contested, possibly because the inflammatory cells perish by the sunlight damage. The most important disorders which are treated in this way and are psoriasis (severe cases of) eczema. UVB therapy can also be used in conditions with light sensitivity, such as sunlight allergy (polymorphous light eruption), or erythropoietic protoporphyria (an inherited, innate sensitivity to light). The skin 'gets used' to UVB: the thickness of the skin increases, and wherein the dose of UV sunburn occurs increases. The dose of UVB gradually increase, until there is just no getting complaints arise, the sensitivity of the patient can be reduced daylight. Possible side effects of UVB therapy (acute) incineration, and in the long term, an increase in the risk of skin cancer.
- UVA has (compared with UVB) has little effect on the skin. With the aid of psoralens, the cells can be made sensitive to UVA light. The treatment is called PUVA. Psoralens can be swallowed, or applied from outside, by dissolving them in bath water or apply as a gel. PUVA is more effective than UVB, but also has more side-effects: skin aging, increased risk of skin cancer. Psoraleentabletten may also provide nausea, sensitivity to light and the damage can be a problem in the summer.
- In recent years, much research into so-called UVA1 therapy: UVA light at a high dose. This therapy seems especially to be able to contribute to the treatment of scleroderma, and possibly eczema. This treatment can currently only in Leiden (LUMC), Amsterdam (AMC) and Nijmegen (UMCN) are performed.
- Treatments with various forms of laser light and flash lamps (IPL), as well as photodynamic therapy (PDT) are not usually considered as a light therapy, although there is used light. Laser and flash lamps can be used in certain types of pigment or vascular abnormalities. Photodynamic therapy is used for skin cancer and precancer.
Neonatology
Newborn infants are sensitive to bilirubin. To excess bilirubin accelerated to let abort are newborns therefore be placed "under the lamp."
Of the light which the lamp produces the blue light (450 nm) effective for the degradation of bilirubin. Usually not only blue light, but just white light (blue light which belongs). This is due to the fact that nursing staff blue light find disturbing. The minimum strength of the blue light, for effective treatment, is 1,000 μW / cm². This is made in the hospital, usually accomplished by a halogen lamp of about 160 W.
On average, the lamps between 500 and 1000 hours. That's about one month per lamp. There is also a more expensive, but more effective, possibility with LEDs. The power can be up to above 3,000 μW / cm². One can check that when the lamp is on the entire time the temperature rises sharply, therefore, there is a fan in the back of the lamp. In LED lamps play this less than halogen lamps.
In severe cases, in addition, there is used a biliblanket. This is a mattress with fiber optic wires in them which blue light is conducted. The blanket of light blue and is usually placed under the baby's head to prevent kernicterus. Of course there is always a chance that things go wrong, but the therapy this risk is reduced as much as possible.
Chronobiology
Light therapy with visible light is the first-choice treatment for winter depression ie seasonal depression (SAD, seasonal affective disorder). It is also used to reduce the effects of jet lag. The unpleasant feelings would be due to a disrupted circadian rhythm. Through therapy biological clock would be put equal again, so proper hormones are produced again at the right time. Of these, in the practice, however claimed successes, even if it was exposed only a portion of the skin. The mechanism remains uncertain.