Editing Seasonal affective disorder (section)

===Light therapy===
Photoperiod-related alterations of the duration of melatonin secretion may affect the seasonal mood cycles of SAD. This suggests that light therapy may be an effective treatment for SAD.<ref>{{cite journal | vauthors = Howland RH | title = Somatic therapies for seasonal affective disorder | journal = Journal of Psychosocial Nursing and Mental Health Services | volume = 47 | issue = 1 | pages = 17–20 | date = January 2009 | pmid = 19227105 | doi = 10.3928/02793695-20090101-07 }}</ref> Light therapy uses a [[light therapy|lightbox]], which emits far more [[Lumen (unit)|lumens]] than a customary incandescent lamp. Bright white [[Full-spectrum light|"full spectrum"]] light at 10,000 lux, blue light at a wavelength of 480nm at 2,500 lux or green (actually cyan or blue-green<ref>{{cite web |vauthors=Jones AZ |title=The Visible Light Spectrum |url=http://physics.about.com/od/lightoptics/a/vislightspec.htm |date=February 15, 2012 |access-date=February 15, 2012 |archive-date=January 3, 2012 |archive-url=https://web.archive.org/web/20120103185102/http://physics.about.com/od/lightoptics/a/vislightspec.htm |url-status=dead }}</ref>) light at a wavelength of 500nm at 350 lux are used, with the first-mentioned historically preferred.<ref name = "Saeeduddin">{{cite journal | vauthors = Loving RT, Kripke DF, Knickerbocker NC, Grandner MA | title = Bright green light treatment of depression for older adults [ISRCTN69400161] | journal = BMC Psychiatry | volume = 5 | pages = 42 | date = November 2005 | pmid = 16283926 | pmc = 1309618 | doi = 10.1186/1471-244X-5-42 | quote = Bright green light was not shown to have an antidepressant effect in the age group of this study, but a larger trial with brighter green light might be of value. | doi-access = free }}</ref><ref>{{cite journal | vauthors = Strong RE, Marchant BK, Reimherr FW, Williams E, Soni P, Mestas R | title = Narrow-band blue-light treatment of seasonal affective disorder in adults and the influence of additional nonseasonal symptoms | journal = Depression and Anxiety | volume = 26 | issue = 3 | pages = 273–8 | year = 2009 | pmid = 19016463 | doi = 10.1002/da.20538 | s2cid = 40649124 | doi-access = free }}</ref>

Bright light therapy is effective<ref name = "Avery2"/> with the patient sitting a prescribed distance, commonly 30–60&nbsp;cm, in front of the box with their eyes open, but not staring at the light source,<ref name = "Avery"/> for 30–60 minutes. A study published in May 2010 suggests that the blue light often used for SAD treatment should perhaps be replaced by green or white illumination.<ref name="doi101126">{{cite journal | vauthors = Gooley JJ, Rajaratnam SM, Brainard GC, Kronauer RE, Czeisler CA, Lockley SW | title = Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light | journal = Science Translational Medicine | volume = 2 | issue = 31 | pages = 31ra33 | date = May 2010 | pmid = 20463367 | pmc = 4414925 | doi = 10.1126/scitranslmed.3000741 }}</ref> Discovering the best schedule is essential. One study has shown that up to 69% of patients find lightbox treatment inconvenient, and as many as 19% stop use because of this.<ref name = "Avery"/>

[[Dawn simulation]] has also proven to be effective; in some studies, there is an 83% better response when compared to other bright light therapy.<ref name = "Avery"/> When compared in a study to [[negative air ionization therapy|negative air ionization]], bright light was shown to be 57% effective vs. dawn simulation 50%.<ref name = "Terman">{{cite journal | vauthors = Terman M, Terman JS | title = Controlled trial of naturalistic dawn simulation and negative air ionization for seasonal affective disorder | journal = The American Journal of Psychiatry | volume = 163 | issue = 12 | pages = 2126–2133 | date = December 2006 | pmid = 17151164 | doi = 10.1176/appi.ajp.163.12.2126 }}</ref> Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks.<ref name = "Avery"/> Certain symptoms like hypersomnia, early insomnia, social withdrawal, and anxiety resolve more rapidly with light therapy than with [[cognitive behavioral therapy]].<ref>{{cite journal | vauthors = Meyerhoff J, Young MA, Rohan KJ | title = Patterns of depressive symptom remission during the treatment of seasonal affective disorder with cognitive-behavioral therapy or light therapy | journal = Depression and Anxiety | volume = 35 | issue = 5 | pages = 457–467 | date = May 2018 | pmid = 29659120 | pmc = 5934317 | doi = 10.1002/da.22739 }}</ref> Most studies have found it effective without use year round, but rather as a seasonal treatment lasting for several weeks, until frequent light exposure is naturally obtained.<ref name = "Lam"/>

[[Light therapy]] can also consist of exposure to sunlight, either by spending more time outside<ref>{{cite web | vauthors = Beck M | date = 1 December 2009 | url = https://www.wsj.com/articles/SB10001424052748703300504574567881192085174?mod=rss_Today%27s_Most_Popular | title = Exercise outdoors: Bright Ideas for Treating the Winter Blues | work = The Wall Street Journal }}</ref> or using a computer-controlled [[heliostat]] to reflect sunlight into the windows of a home or office.<ref>{{cite web | url = http://www.practicalsolar.com/applications.html | title = Applications: Health | access-date = June 9, 2009 | publisher = Practical Solar | url-status = dead | archive-url = https://web.archive.org/web/20090615153220/http://www.practicalsolar.com/applications.html | archive-date = June 15, 2009 | df = mdy-all }}</ref><ref>{{cite web | url = http://www.newyorkhousemagazine.com/pages/full_story?page_label=home_main_top&id=2631630&widget=push&instance=home_green_future&article-Grab%20the%20Sun%20With%20Heliostats%20=&open=& | archive-url = https://web.archive.org/web/20091004205721/http://www.newyorkhousemagazine.com/pages/full_story?page_label=home_main_top&id=2631630&widget=push&instance=home_green_future&article-Grab%20the%20Sun%20With%20Heliostats%20=&open=& | url-status = dead | archive-date = October 4, 2009 | title = Grab the Sun With Heliostats | publisher = New York House | access-date = December 8, 2009 | date = June 1, 2009 }}</ref> Although light therapy is the leading treatment for seasonal affective disorder, prolonged direct sunlight or artificial lights that don't block the ultraviolet range should be avoided, due to the threat of [[skin cancer]].<ref>{{cite journal | vauthors = Osborn J, Raetz J, Kost A | title = Seasonal affective disorder, grief reaction, and adjustment disorder | journal = The Medical Clinics of North America | volume = 98 | issue = 5 | pages = 1065–77 | date = September 2014 | pmid = 25134873 | doi = 10.1016/j.mcna.2014.06.006 }}</ref>

The evidence base for light therapy as a preventive treatment for seasonal affective disorder is limited.<ref name=":0">{{cite journal | vauthors = Nussbaumer-Streit B, Forneris CA, Morgan LC, Van Noord MG, Gaynes BN, Greenblatt A, Wipplinger J, Lux LJ, Winkler D, Gartlehner G | display-authors = 6 | title = Light therapy for preventing seasonal affective disorder | journal = The Cochrane Database of Systematic Reviews | volume = 3 | pages = CD011269 | date = March 2019 | issue = 4 | pmid = 30883670 | pmc = 6422319 | doi = 10.1002/14651858.CD011269.pub3 }}</ref> The decision to use light therapy to treat people with a history of winter depression before depressive symptoms begin should be based on a person's preference of treatment.<ref name=":0" />