Light therapy, also known as bright light therapy, heliotherapy or phototherapy, is defined as exposure to daylight or to specific wavelengths of light using polychromatic polarised light, lasers, light-emitting diodes, fluorescent lamps, dichroic lamps or very bright, full-spectrum light. The light is administered for a prescribed amount of time and, in some cases, at a specific time of day. Light therapy which strikes the retina of the eyes is used to treat circadian rhythm disorders such as delayed sleep phase disorder, and is also used to treat seasonal affective disorder (SAD) by exposure to artificial light. Seasonal affective disorder is a type of depression that occurs at a certain time each year, usually in the fall or winter. Light therapy is also associated with the treatment of skin disorders, such as psoriasis, acne vulgaris, eczema and neonatal jaundice. Light therapy is NOT the same as Chromotherapy.
Light therapy involves exposure to intense levels of light under controlled conditions. The recommend light therapy system consists of a set of fluorescent bulbs installed in a box with a diffusing screen and set up on a desk or table top at which a person can sit comfortably for the treatment session. Treatment consists simply of sitting close to the light box with the lights on and the person's eyes open.
Looking at the lights is not something that is recommend; instead, people are free to engage in activities such as writing, reading, or eating a meal. What is important is to orient your body and head towards the lights, concentrating on activities on the surfaces illuminated by the lights and not on the lights themselves. Treatment sessions may last from fifteen minutes to three hours, one or two times each day, depending upon the person's individual needs and the equipment they are using.
The average length of a light therapy session for a system delivering ten-thousand lux illumination is much shorter than for two-thousand-five-hundred lux. In clinical trials with more than 100 people with SAD who used a ten-thousand lux system with UV-filtered light diffusion and angular tilt for thirty minutes each day, around three-fourths showed great improvement in regards to depression. In another experiment, it was found that thirty minutes was an unnecessarily long period of exposure for some people, while others required one-hour exposures to experience the desired effect.
Early research studies used full-spectrum bulbs producing bright light similar in color composition to outdoor daylight, in contrast to the color of regular fluorescent or incandescent lighting. The technology is evolving quickly; however, and manufacturers now offer systems that are effective using cool-white, bi-axial and triphosphor lamps. What seems to be critical is that the level of light produced match that of light outside shortly after sunrise or before sunset. Light intensity is a crucial dosing dimension of the therapy. Systems deliver different amounts of light and people differ in their response to levels of light.
Another important factor is the time of day light therapy is used. Many people who experience winter depression respond best to treatment first thing after waking up. Other people receive better results with evening light. It is necessary to determine the optimum time of day for each person.
Some people who are very light-sensitive, who live and work in dim environments, might feel improvement with increased exposure to usual room lighting. Research has revealed; however, that the majority of people with SAD and winter doldrums require exposure to levels of light far higher than usual ceiling fixtures and indoor lamps provide. Such therapeutic levels are five to twenty times greater than average indoor illumination in the person's office or at home.
Researchers at more than fifteen medical centers and clinics in America and around the world have had great success with light therapy in people with clear histories of SAD for at least several years. Notable improvement is usually observed within a week, if not sooner and symptoms usually return in around the same amount of time when the lights are withdrawn. The majority of users can maintain a consistent daily schedule starting, as needed, in Autumn or Winter and usually continuing until the end of April, by which time outdoor light is enough to maintain high energy and a positive mood. Some people can skip treatments for one to three days - longer on occasion, without ill effect, yet the majority begin to slump rapidly when treatment is interrupted.
The therapeutic level of illumination has a number of known physiological effects, although its therapeutic mechanism remains unclear. Blood levels of the light-sensitive hormone, 'melatonin,' which might be unusually high at certain times of the day, are quickly reduced by light exposure. Depending on when bright light is presented, the body's clock, which controls daily rhythms of hormone secretion, body temperature and sleep patterns, shifts ahead or is delayed when stimulated by light.
These physiological time shifts might be the basis of the therapeutic response. Light might also amplify the day-night difference in these rhythms. Research into the potential mechanisms is currently underway and the final answer has not yet been achieved.
Side-effects of light therapy have been minimal. While a small population of people experience eyestrain or irritation, headaches, or nausea at the start of treatment, these are commonly mild and fade after a few days. The most dramatic side effect, which happens very infrequently, is a switch to an overactive state - during which one might have difficulty with sleeping, become irritable or restless and feel, 'too high,' or speedy.
People who have experienced such states in late Spring or Summer are especially vulnerable and guidance by a clinician in the use of light therapy is particularly important. If eye irritation persists it may be alleviated by sitting farther from the lights, using them for shorter periods of time, or by installing a humidifier. Some people report disturbing sensations of visual glare under bright light therapy, which may be alleviated by use of the tilted light box design. A major source of visual glare is short-wavelength blue light, which is a part of the white light used for therapy. Blue light may be screened out through use of recently developed eyeglass lenses which maximize transmission of longer wavelengths without significantly affecting lux levels.
While no hazard is suspected and some women who are pregnant have used the treatment with success, light therapy has not been systematically evaluated during pregnancy. Three relevant clinical trials; however, are underway and cover a variety of interventions for antepartum depression – whether or not the depression happens in Winter.
Research studies exclude people with retinal or ocular pathology, such as cataracts, glaucoma, retinopathy or retinal detachment who may be at risk. No negative effects of light therapy has been found in opthalmologic examinations of people with SAD, although because this is a newer technology - caution is warranted.
In the sense that a doctor suggests and supervises light therapy, the method is approved. The Food and Drug Administration (FDA) has not ruled one way or another and in this sense the lights are not being considered as a new medication. People do not need a prescription for the lights, although anyone who experiences serious depression should definitely pursue a doctor's recommendation before buying a light therapy unit and then use it under a doctor's supervision.
Insurance reimbursement for the cost of light therapy apparatus is not consistent. Some people have made successful claims based on their doctor's statement that the lights are medically indicated and effective for the person. Medicaid does not cover the cost of light therapy. If the insurance policy covers psychotherapy or psychiatric care, it is likely that it will reimburse for clinical sessions involved in the diagnosis of SAD, evaluation for light treatment and follow-up appointments.
Light therapy technology is fairly new and several manufacturers are producing new models every year. Prices have ranged from around $360-$500. Breakthroughs in design might reduce the cost in the future.
It is not recommended that people attempt home construction of light therapy units. Output needs to be specifically calibrated for the appropriate effect. A danger of creating heat or electrical hazards exists. Light therapy units on the market should been evaluated for visual comfort, output intensity, maximum transmission with minimal heat build-up and clinical efficacy in documented research trials. Be sure to check into these factors prior to purchasing a light therapy unit.
Light Therapy: Overview of Research and Literature - Research and literature on the therapeutic benefits of light therapy to living tissues and organisms - Disabled World.