Light therapy or phototherapy consists of exposure to specific wavelengths of light using lasers, LEDs, fluorescent lamps, dichroic lamps or very bright, full-spectrum light, for a prescribed amount of time. It has proven effective in treating Acne vulgaris, seasonal affective disorder (SAD), and for some people it has ameliorated delayed sleep phase syndrome. It has recently been shown effective in non-seasonal depression. Proponents claim demonstrable benefits for skin conditions such as psoriasis and, more controversially, a degree of "skin rejuvenation."

Acne vulgaris

Visible blue light in the range 440nm has been shown to activate porphyrins in Propionibacterium acnes which damage and ultimately kill the bacteria by creating free radicals. Application of the light for 3 consecutive days has been shown to reduce the bacteria in the pores by 99.9%. Since there are few porphorins naturally found in the skin, the treatment is believed safe; although eye protection is necessary due to light sensitive chemicals in the retina. The light is usually created by fluorescent lamps, bright LEDs or dichroic filament bulbs.

Treatment is often accompanied with application of red light which has been shown to activate ATP in human skin cells, and seems to improve response rates.

Overall improvements of 80% can be found over 3 months; most studies show that it performs better than Benzoyl peroxide but treatment is far better tolerated. However approximately 10% of users see no improvement.British Journal of dermatology 2000 effectiveness of blue/red light treatments

Home use light boxes usually work well, are effective for people with long-term acne; and are likely to be cheaper than dermatologist office light treatments, and can be repeated over several years for negligible cost. As of 2006 even though they are not cheap, the cost is on a par with the total cost of benzoyl peroxide, moisturiser and facial washes over the total life of the light box, and the light boxes may yet get cheaper due to economies of scale.

Application in a dermatologist's office is usually much more costly, and not necessarily any more effective, but the visible blue light is sometimes used with off-label use of aminolevulinic acid; this causes the bacteria to generate more than normal quantities of porphyrins and this greatly improves response. Whilst temporary redness and edema is experienced, this can give over a year of clearance with just a few applications.

See also Photobiomodulation for information regarding tissue regeneration and pain relief with laser and LED light.

There is some skepticism and lack of data over some of the treatments of acne vulgaris through visible light, particularly the relatively experimental photodynamic treatments. For more information.Aetna policy bulletin re: Phototherapy for Acne

Neonatal jaundice

Light energy creates isomerization of the bilirubin and consequently transformation into compounds that the newborn can excrete via urine and stools.

Seasonal affective disorder

Full sunlight is preferred for seasonal affective disorder. Other treatments are based upon infrared light exposure. There are a number of products (such as light boxes) using very intense artificial illumination that are effective for Seasonal Affective Disorder. These products must provide 10,000 lux or more directed angularly at the user's eyes, while filtering out any harmful ultraviolet radiation. Modern light boxes do not emit ultraviolet radiation. New research indicates that using only certain wavelengths of light (i.e., the "blue" wavelengths) is at least as efficacious as using 10,000 lux, at least until one approaches old age, when blue light no longer is more effective than red or green. Other studies have shown that blue light may play a role in developing age-related macular degeneration (ARMD)^***.

Non-seasonal depression

Only recently have clinical studies been conducted which specifically excluded all patients with any degree of seasonality.Goel N, Terman M, Terman JS, Macchi MM, Stewart JW. Controlled trial of bright light and negative air ions for chronic depression. Psychological Medicine 2005;35 Before these studies, there was suspicion that any depressed patients who benefitted from light treatment were really only having the SAD component of their depression treated. However, light therapy is now an established treatment for depression, regardless of seasonality,Wirz-Justice A, Benedetti F, Berger M, Lam RW, Martiny K, Terman M, Wu J. Chronotherapeutics (light and wake therapy) in affective disorders. Psychological Medicine 2005;35Science News, April 23, 2005 - Mood Brighteners: Light Therapy Gets Nod as Depression Buster" by Bruce Bower and has certain advantages over drugs, in that it might take less time to see a benefit (typically antidepressant drugs take several weeks to reach full effectiveness).

Delayed sleep phase syndrome

When treating delayed sleep phase syndrome, the timing of the exposure is critical. The light must be provided as soon after arising as possible to achieve any effect. Some users have reported success with lights that turn on shortly before waking (dawn simulation).

Psoriasis

A feature of Psoriasis is excessively fast turnover of skin layers. Application of UV radiation to the skin damages it and thus slows this, and some improvements are seen in the condition.

See Also: PUVA

Tanning

Tanning is caused by the effects of two different types of Ultraviolet, UVA and UVB. Detailed information regarding the differences between UVA and UVB wavelengths can be found here http://www.beatpsoriasis.com/documentation.htm

'Antiaging'

Visible red light activates ATP in skin cells and increase the rate of production of collagen for a few days, giving a lifting effect. No permanent improvement of skin aging has been demonstrated, but completion of the healing of skin damage does seem to proceed faster.

Safety of phototherapy

Ultraviolet light causes progressive damage to human skin. This is mediated by genetic damage, collagen damage, as well as destruction of vitamin A and Vitamin C in the skin and free radical generation.

Visible blue light has been suggested to cause DNA breaks, but carcinogenesis has not been demonstrated, and enzymes within the cells are believed to repair the breaks reasonably well. However cancer has been induced in cells with deliberately damaged repair mechanisms.

Modern phototherapy lamps used in the treatment of Seasonal Affective Disorder do not emit ultraviolet light and are considered safe and effective for the intended purpose, as long as photosensitizing drugs are not being taken at the same time and in the absence of any existing eye conditions. Light therapy is a mood altering treatment, as just as with drug treatments, there is a possibility of triggering a manic state from a depressive state, causing anxiety, and other side effects. While these side-effects are usually controllable, it is recommended that patients undertake light-therapy under the supervision of an experienced clinician, rather than attempting to self-medicate. Terman M, Terman JS - Light therapy for seasonal and nonseasonal depression: efficacy, protocol, safety, and side effects. CNS Spectr. 2005;10:647-63

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