Light therapy or phototherapy (classically referred to as heliotherapy) consists of 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, usually controlled with various devices. The light is administered for a prescribed amount of time and, in some cases, at a specific time of day.
Common use of the term is associated with the treatment of skin disorders (chiefly psoriasis), sleep disorder and some psychiatric disorders. Light therapy directed at the skin is also used to treat acne vulgaris, eczema and neonatal jaundice. Light therapy which strikes the retina of the eyes is used to treat circadian rhythm disorders such as delayed sleep phase disorder and can also be used to treat seasonal affective disorder, with some support for its use also with non-seasonal psychiatric disorders.
- 1 Medical uses
- 2 Techniques
- 3 Risks and complications
- 4 History
- 5 See also
- 6 References
- 7 External links
Two forms of phototherapy exist, non-targeted phototherapy (from sunlight or a light box), and targeted-phototherapy, in which light is administered to a specific, localized area of the skin. Current targeted phototherapy is administered via excimer laser, elemental gas lamp, or via LED light. Current FDA cleared devices on the market include XTRAC excimer laser, BClear, Theralight, and Psoria-Light LED phototherapy. Targeted phototherapy is administered in a doctor's office and is only administered to the affected skin, not the entire body, thus sparing healthy skin from UV rays which may lead to other health issues including skin cancer. While different wavelengths work for different conditions, treatment is most often done with narrow band UVB (NB-UVB) as this is the safest wavelength. Non-targeted phototherapy can be delivered at doctor's office or at home via prescription (USA) using a booth, multidirectional unit, or wand. The unaffected skin is simply covered. Several devices are FDA-approved for home including the Panosol 3D and Richmond Light and Solarc Handheld.
In psoriasis, UVB phototherapy has been shown to be effective. A feature of psoriasis is localized inflammation mediated by the immune system. Ultraviolet radiation is known to suppress the immune system and reduce inflammatory responses. Light therapy for skin conditions like psoriasis usually use NB-UVB (311 nm wavelength) though may use UV-A (315–400 nm wavelength) or UV-B (280–315 nm wavelength) light waves. UV-A, combined with psoralen, a drug taken orally, is known as PUVA treatment. In UVB Phototherapy the exposure time is very short (seconds to minutes depending on intensity of lamps). The time is controlled with a timer that turns off the lamps after the treatment time ends.
One percent of the population suffer from vitiligo, and Narrowband UVB Phototherapy is an effective treatment. "NB-UVB phototherapy results in satisfactory repigmentation in our vitiligo patients and should be offered as a treatment option."
Evidence for light therapy and lasers in acne vulgaris as of 2012 is not sufficient to recommend them. While light therapy appears to provide short term benefit, there is a lack of long term outcome data or data in those with severe acne.
According to the American Cancer Society, there is some evidence that ultraviolet light therapy may be effective in helping treat certain kinds of skin cancer, and ultraviolet blood irradiation treatment is established for this application. However, alternative uses of light for cancer treatment – light box therapy and colored light therapy – are not supported by evidence.
Other skin conditions
Some case studies have found low-level laser light to be possibly helpful as an adjunctive treatment in wound healing, although a review of the overall scientific literature does not support the use of low-level laser therapy for this purpose.
Seasonal affective disorder
While full sunlight is preferred for seasonal affective disorder (SAD), light boxes may be effective for the treatment of the condition. Light boxes for seasonal affective disorder are designed to filter out most UV light, which can cause eye and skin damage. Mayo Clinic states that light therapy is of proven effectiveness for treating seasonal affective disorder and light therapy is seen as its main form of treatment. Controlled-trial comparisons with antidepressants show equal effectiveness, with less expense and more rapid onset of therapeutic benefit, though a minority of patients may not respond to it. Direct sunlight, reflected into the windows of a home or office by a computer-controlled mirror device called a heliostat, has also been used as a type of light therapy for the treatment of SAD.
The effectiveness of light therapy for treating SAD may be linked to the fact that light therapy makes up for lost sunlight exposure and resets the body's internal clock.
It is possible that response to light therapy for SAD could be season dependent.
Light therapy has also been suggested in the treatment of non-seasonal depression and other psychiatric disturbances, including major depressive disorder, bipolar disorder and postpartum depression. A meta-analysis by the Cochrane Collaboration concluded that "for patients suffering from non-seasonal depression, light therapy offers modest though promising antidepressive efficacy." A more recent meta-analysis from Journal of Affective Disorders confirms this and is even more hopeful: "Overall, bright light therapy is an excellent candidate for inclusion into the therapeutic inventory available for the treatment of nonseasonal depression today, as adjuvant therapy to antidepressant medication, or eventually as stand-alone treatment for specific subgroups of depressed patients."
Circadian rhythm sleep disorder
- Chronic CRSD
In the management of circadian rhythm disorders such as delayed sleep phase disorder (DSPD), the timing of light exposure is critical. For DSPD, the light must be provided to the retina as soon after spontaneous awakening as possible to achieve the desired effect, as shown by the phase response curve for light in humans. Some users have reported success with lights that turn on shortly before awakening (dawn simulation). Morning use may also be effective for non-24-hour sleep–wake disorder, while evening use is recommended for advanced sleep phase disorder.
- Situational CRSD
Light therapy is used to treat cases of neonatal jaundice through the isomerization of the bilirubin and consequently transformation into compounds that the newborn can excrete via urine and stools. A common treatment of neonatal jaundice is the bili light.
Photodynamic therapy is a form of phototherapy using nontoxic light-sensitive compounds that are exposed selectively to light, whereupon they become toxic to targeted malignant and other diseased cells
The production of the hormone melatonin, a sleep regulator, is inhibited by light and permitted by darkness as registered by photosensitive ganglion cells in the retina. To some degree, the reverse is true for serotonin, which has been linked to mood disorders. Hence, for the purpose of manipulating melatonin levels or timing, light boxes providing very specific types of artificial illumination to the retina of the eye are effective.
Light therapy uses either a light box which emits up to 10,000 lux of light at a specified distance, much brighter than a customary incandescent lamp, or a lower intensity of specific wavelengths of light from the blue (470 nm) to the green (525 nm) areas of the visible spectrum. Newer light therapy devices use LED technology, making them much smaller and more convenient for users. A 1995 study showed that green light therapy at doses of 350 lux produces melatonin suppression and phase shifts equivalent to 10,000 lux white light therapy, but another study published in May 2010 suggests that the blue light often used for SAD treatment should perhaps be replaced by green or white illumination, because of a possible involvement of the cones in melatonin suppression.
In treatment, the patient's eyes are to be at a prescribed distance from the light source with the light striking the retina. This does not require looking directly into the light.
Considering three major factors – clinical efficacy, ocular and dermatologic safety, and visual comfort – CET recommends the following criteria for light box selection:
- Light boxes should have been tested successfully in peer-reviewed clinical trials.
- The box should provide 10,000 LUX of illumination at a comfortable sitting distance. Product specifications are often missing or unverified; illuminance can be controlled using a light meter.
- Fluorescent lamps should have a smooth diffusing screen that filters out ultraviolet (UV) rays. UV rays are harmful to the eyes and skin.
- Blue light is known to be superior to red light in managing depressive symptoms which have a seasonal pattern.
- The light should be projected downward toward the eyes at an angle to minimize aversive visual glare.
- Smaller is not better; when using a compact light box, even small head movements will take the eyes out of the therapeutic range of the light.
Risks and complications
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. Ultraviolet light is also known to be a factor in formation of cataracts. Researchers have questioned whether limiting blue light exposure could reduce the risk of age-related macular degeneration.
Modern phototherapy lamps used in the treatment of seasonal affective disorder and sleep disorders either filter out or 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, and 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.
There are few absolute contraindications to light therapy, although there are some circumstances in which caution is required. These include when a patient has a condition that might render his or her eyes more vulnerable to phototoxicity, has a tendency toward mania, has a photosensitive skin condition, or is taking a photosensitizing herb (such as St. John's wort) or medication. Patients with porphyria should avoid most forms of light therapy. Patients on certain drugs such as methotrexate or chloroquine should use caution with light therapy as there is a chance that these drugs could cause porphyria.
Side effects of light therapy for sleep phase disorders include jumpiness or jitteriness, headache, and nausea. Some nondepressive physical complaints (such as poor vision and skin rash or irritation) may improve with light therapy.
Many ancient cultures practiced various forms of heliotherapy, including people of the Ancient Greece, Ancient Egypt, and Ancient Rome. The Inca, Assyrian and early German settlers also worshipped the sun as a health bringing deity. Indian medical literature dating to 1500 BC describes a treatment combining herbs with natural sunlight to treat non-pigmented skin areas. Buddhist literature from about 200 AD and 10th-century Chinese documents made similar references.
Faroese physician Niels Finsen is believed to be the father of modern phototherapy. He developed the first artificial light source for this purpose, and used his invention to treat lupus vulgaris. He received the Nobel Prize in Physiology or Medicine in 1903.
Since then a large array of treatments have been developed from the use of controlled light. Though the popular consumer understanding of "light therapy" is associated with treating seasonal affective disorder and skin conditions like psoriasis, other applications include the application of low level laser, red light, near-infrared and ultraviolet lights for pain management, hair growth, skin treatments, and accelerated wound healing.
- Blood irradiation therapy
- Deep penetrating light therapy
- Free-running sleep
- Emotional Transformation Therapy
- Low level laser therapy
- Sun tanning
- Diffey BL (1980). "Ultraviolet radiation physics and the skin". Phys. Med. Biol. 25 (3): 405–426. doi:10.1088/0031-9155/25/3/001. PMID 6996006.
- "What is Psoriasis: What Causes Psoriasis?". 29 January 2012. Retrieved 11 July 2012.
- Adauwiyah J, Suraiya HH (December 2010). "A retrospective study of narrowband-UVB phototherapy for treatment of vitiligo in Malaysian patients". Med. J. Malaysia 65 (4): 297–9. PMID 21901949.
- Titus S, Hodge J (October 2012). "Diagnosis and treatment of acne". Am Fam Physician 86 (8): 734–40. PMID 23062156.
- Hamilton FL, Car J, Lyons C, Car M, Layton A, Majeed A (June 2009). "Laser and other light therapies for the treatment of acne vulgaris: systematic review". Br. J. Dermatol. 160 (6): 1273–85. doi:10.1111/j.1365-2133.2009.09047.x. PMID 19239470.
- "Light Therapy". American Cancer Society. 14 April 2011. Retrieved September 2013.
- Sutterfield R (2008 Jan–Feb). "Light therapy and advanced wound care for a neuropathic plantar ulcer on a Charcot foot". J Wound Ostomy Continence Nurs 35 (1): 113–115. doi:10.1097/01.WON.0000308628.60958.d9. PMID 18199948. 
- Posten W, Wrone DA, Dover JS, Arndt KA, Silapunt S, Alam M (March 2005). "Low-level laser therapy for wound healing: mechanism and efficacy". Dermatol Surg 31 (3): 334–40. doi:10.1111/j.1524-4725.2005.31086. PMID 15841638.
- "Seasonal affective disorder treatment Choosing a light box". Mayo Clinic. 2010-10-01. Retrieved 2011-01-07.
- "Light therapy". Mayo Clinic. 7 October 2010. Retrieved 11 July 2012.
- Lam, RW, Levitt AJ, Levitan RD, Enns M, Morehouse R, Michalak EE, Tam EM (2006). "The Can-SAD Study: A Randomized Controlled Trial of the Effectiveness of Light Therapy and Fluoxetine in Patients With Winter Seasonal Affective Disorder.". American Journal of Psychiatry 163:805–812. Retrieved 2012-02-09.
- "Applications: Health". Practical Solar. Retrieved 2009-06-09.
- "Grab the Sun With Heliostats". New York House. 2009-06-01. Retrieved 2009-12-08.
- "Light Therapy – Topic Overview". WebMD. 30 June 2009. Retrieved 11 July 2012.
- Thompson C, Stinson D, Smith A (September 1990). "Seasonal affective disorder and season-dependent abnormalities of melatonin suppression by light". Lancet 336 (8717): 703–6. doi:10.1016/0140-6736(90)92202-S. PMID 1975891.
- Benedetti F, Colombo C, Pontiggia A, Bernasconi A, Florita M, Smeraldi E, (2003) Morning light treatment hastens the antidepressant effect of citalopram: a placebo-controlled trial, J Clin Psychiatry. Jun; 64(6) 648-53.
- Prasko J (November 2008). "Bright light therapy". Neuro Endocrinol. Lett. 29 Suppl 1: 33–64. PMID 19029878.
- Terman M (December 2007). "Evolving applications of light therapy" (pdf). Sleep Med Rev 11 (6): 497–507. doi:10.1016/j.smrv.2007.06.003. PMID 17964200.
- Tuunainen, A; Kripke, DF; Endo, T (2004). "Light therapy for non-seasonal depression". In Tuunainen, Arja. Cochrane Database of Systematic Reviews (2): CD004050. doi:10.1002/14651858.CD004050.pub2. PMID 15106233.
- Even, C; Schröder, CM; Friedman, S; Rouillon, F (2008). "Efficacy of light therapy in nonseasonal depression: A systematic review". Journal of Affective Disorders 108 (1–2): 11–23. doi:10.1016/j.jad.2007.09.008. PMID 17950467.
- Smith MR, Eastman CI (December 2008). "Night shift performance is improved by a compromise circadian phase position: study 3. Circadian phase after 7 night shifts with an intervening weekend off". Sleep 31 (12): 1639–45. PMC 2603486. PMID 19090319.
- Brown GM, Pandi-Perumal SR, Trakht I, Cardinali DP (March 2009). "Melatonin and its relevance to jet lag". Travel Med Infect Dis 7 (2): 69–81. doi:10.1016/j.tmaid.2008.09.004. PMID 19237140.
- Newman TB, Kuzniewicz MW, Liljestrand P, Wi S, McCulloch C, Escobar GJ (May 2009). "Numbers needed to treat with phototherapy according to American Academy of Pediatrics guidelines". Pediatrics 123 (5): 1352–9. doi:10.1542/peds.2008-1635. PMC 2843697. PMID 19403502.
- Aetna policy bulletin re: Phototherapy for Acne
- Wright HR, Lack LC, Kennaway DJ. (March 2004). "Differential effects of light wavelength in phase advancing the melatonin rhythm". J. Pineal Res. 36 (2): 140–4. doi:10.1046/j.1600-079X.2003.00108.x. PMID 14962066.
- Saeeduddin Ahmed, Neil L Cutter, Alfred J. Lewy, Vance K. Bauer, Robert L Sack and Mary S. Cardoza (1995). "Phase Response Curve of Low-Intensity Green Light in Winter Depressives". Sleep Research 24: 508. "The magnitude of the phase shifts [using low-level green light therapy] are comparable to those obtained using high-intensity white light in winter-depressives."
- Michel A. Paul, James C. Miller, Gary Gray, Fred Buick, Sofi Blazeski and Josephine Arendt (July 2007). "Circadian Phase Delay Induced by Phototherapeutic Devices". Sleep Research 78 (7): 645–652.
- J.J. Gooley, S.M.W. Rajaratnam, G.C. Brainard, R.E. Kronauer, C.A. Czeisler, S.W. Lockley (May 2010). "Spectral Responses of the Human Circadian System Depend on the Irradiance and Duration of Exposure to Light". Science Translational Medicine 2 (31): 31–33. doi:10.1126/scitranslmed.3000741. PMID 20463367.
- "Light Box Selection". Center for Environmental Therapeutics. CET. Retrieved 25 May 2011.
- Glickman, G; Byrne, B; Pineda, C; Hauck, WW; Brainard, GC (2006 Mar 15). "Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs).". Biological Psychiatry 59 (6): 502–7. doi:10.1016/j.biopsych.2005.07.006. PMID 16165105.
- Glazer-Hockstein C, Dunaief JL (January 2006). "Could blue light-blocking lenses decrease the risk of age-related macular degeneration?". Retina (Philadelphia, Pa.) 26 (1): 1–4. doi:10.1097/00006982-200601000-00001. PMID 16395131.
- Terman M, Terman JS (August 2005). "Light therapy for seasonal and nonseasonal depression: efficacy, protocol, safety, and side effects". CNS Spectr 10 (8): 647–63; quiz 672. PMID 16041296.
- "Bright Light May Boost Testosterone". WebMD. Retrieved 2008-12-15.
- Danilenko KV, Samoilova EA (2007). "Stimulatory effect of morning bright light on reproductive hormones and ovulation: results of a controlled crossover trial". PLoS Clin Trials 2 (2): e7. doi:10.1371/journal.pctr.0020007. PMC 1851732. PMID 17290302.
- Gagarina, AK (2007-12-08). "Light Therapy Diagnostic Indications and Contraindications". American Medical Network. Retrieved 2009-06-09.
- Roger DR (2007-12-04). "Practical aspects of light therapy". American Medical Network. Retrieved 2009-06-09.
- F. Ellinger Medical Radiation Biology Springfield 1957
Media related to Phototherapy at Wikimedia Commons