What is light therapy?
Light therapy uses the effect of different forms of light on the body. Classic light therapy uses irradiation with bright fluorescent light, which physically corresponds to sunlight.
When is light therapy useful?
Light therapy is used for various illnesses. Depending on the type of illness, either classic light therapy or UV light therapy can be useful.
Classic light therapy
It is possible to use classic light therapy (supportive) for the following illnesses
- depression
- migraine
- sleep disorders
- eating disorders
- burn-out
The bright light of the light shower brings the internal clock back into sync and at the same time ensures that the serotonin level increases again.
UV light therapy
UV-A and UV-B radiation (ultraviolet radiation) is mainly used to treat dermatological diseases:
- Psoriasis
- White spot disease (vitiligo)
- Neurodermatitis (atopic eczema)
- T-cell lymphomas of the skin (mycosis fungoides)
- Graft-versus-host disease – a systemic disease after bone marrow transplantation
PUVA (psoralen and UV-A phototherapy) is one of the most effective forms of light therapy.
Read our article PUVA to find out how psoralen and UV-A phototherapy works and what you need to bear in mind.
How does light therapy work?
What happens during classic light therapy?
Successful light therapy requires an illuminance of at least 2,500 to 10,000 lux. This requires a special light therapy device, as normal light bulbs only emit around 300 to 800 lux.
The light shower emits a fluorescent, diffuse light with a broad spectrum, which corresponds most closely to natural sunlight. Light therapy is most effective when the light is absorbed via the retina of the eye. It thus reaches the so-called suprachiasmatic nucleus, a part of the brain that plays a decisive role as a pulse generator for the cicardian rhythm (diurnal rhythm) and thus also for serotonin and melatonin levels.
Light therapy normally takes effect after three to four days. If the light therapy has no effect during this time, the light intensity can be increased or the lighting duration extended. An additional evening light shower is also helpful. Light therapy usually lasts one week, but can be repeated or applied regularly in the event of relapses. To prevent seasonal depression, some sufferers start preventive light therapy as early as October.
What happens during UV-A or UV-B phototherapy?
What happens during color light therapy?
A special case is neonatal jaundice. In this case, a breakdown product of red blood cells, bilirubin, accumulates in the newborn’s body and stains the skin and eyes yellow. If the bilirubin exceeds a certain level, this can lead to brain damage. This can be counteracted with colored light therapy. Short-wave blue light helps the newborn to excrete the bilirubin more quickly.
What are the risks of light therapy?
There are no known serious side effects of light therapy. Headaches, eye irritation or a feeling of tightness in the skin rarely occur. However, these symptoms subside after a few hours. Blue light therapy can cause skin rashes, increased fluid loss and diarrhea in newborns. The UV radiation from phototherapy basically acts like natural sunlight and, in excess, is potentially carcinogenic and accelerates skin ageing.
What do I need to bear in mind when undergoing light therapy?
Regular treatment is also important, even on symptom-free days. Evening light therapy should only be carried out in consultation with your doctor, as a light shower can disrupt the circadian sleep-wake rhythm. Certain medications such as tricyclic antidepressants, neuroleptics or lithium increase light sensitivity. For this reason, an ophthalmologist’s examination should be carried out before starting light therapy. Prior consultation with an ophthalmologist is also recommended for all eye diseases.
UV phototherapy should never be used on people with genetic defects with an increased sensitivity to light or an increased risk of skin cancer (for example: xeroderma pigmentosum, Cockayne syndrome and Bloom syndrome). Caution is also advised in the case of a history of skin cancer or severe, radiation-induced skin damage. Discuss the risks and benefits of the therapy with your doctor.
