Editing Circadian rhythm (section)

==== Indoor lighting ====
Lighting requirements for circadian regulation are not simply the same as those for vision; planning of indoor lighting in offices and institutions is beginning to take this into account.<ref>{{cite journal | vauthors = Rea MS, Figueiro M, Bullough J |date=May 2002 |title=Circadian photobiology: an emerging framework for lighting practice and research |journal=Lighting Research & Technology |volume=34 |issue=3 |pages=177–187 |doi=10.1191/1365782802lt057oa |s2cid=109776194}}</ref> Animal studies on the effects of light in laboratory conditions have until recently considered light intensity ([[irradiance]]) but not color, which can be shown to "act as an essential regulator of biological timing in more natural settings".<ref>{{cite journal | vauthors = Walmsley L, Hanna L, Mouland J, Martial F, West A, Smedley AR, Bechtold DA, Webb AR, Lucas RJ, Brown TM | title = Colour as a signal for entraining the mammalian circadian clock | journal = PLOS Biology | volume = 13 | issue = 4 | pages = e1002127 | date = April 2015 | pmid = 25884537 | pmc = 4401556 | doi = 10.1371/journal.pbio.1002127 | doi-access = free }}</ref>

Blue LED lighting suppresses [[melatonin]] production five times more than the orange-yellow [[Sodium-vapor lamp|high-pressure sodium (HPS) light]]; a [[metal halide lamp]], which is white light, suppresses melatonin at a rate more than three times greater than HPS.<ref>{{Cite journal | vauthors = Hardt R |date=1970-01-01 |title=The Dangers of LED-Blue light-The Suppression of Melatonin-Resulting in-Insomnia-And Cancers {{pipe}} Robert Hardt |url=https://www.academia.edu/5960717 |access-date=2016-12-24 |website=Academia.edu}}{{Dead link|date=December 2021|bot=InternetArchiveBot|fix-attempted=yes}}</ref> [[Biology of depression#Circadian rhythm|Depression symptoms]] from long term nighttime light exposure can be undone by returning to a normal cycle.<ref>{{cite journal | vauthors = Bedrosian TA, Nelson RJ | title = Timing of light exposure affects mood and brain circuits | journal = Translational Psychiatry | volume = 7 | issue = 1 | pages = e1017 | date = January 2017 | pmid = 28140399 | pmc = 5299389 | doi = 10.1038/tp.2016.262 }}</ref>