Editing Chronobiology (section)

==Research developments==
;Light and melatonin
More recently, [[light therapy]] and [[melatonin (medication)|melatonin]] administration have been explored by [[Alfred J. Lewy]] ([[OHSU]]), [[Josephine Arendt]] ([[University of Surrey]], UK) and other researchers as a means to reset animal and human circadian rhythms. Additionally, the presence of low-level light at night accelerates circadian re-entrainment of hamsters of all ages by 50%; this is thought to be related to simulation of moonlight.<ref>{{Cite journal | last1 = Frank | first1 = D. W. | last2 = Evans | first2 = J. A. | last3 = Gorman | first3 = M. R. | doi = 10.1177/0748730409360890 | title = Time-Dependent Effects of Dim Light at Night on Re-Entrainment and Masking of Hamster Activity Rhythms | journal = Journal of Biological Rhythms | volume = 25 | issue = 2 | pages = 103–112 | year = 2010 | pmid =  20348461| s2cid = 41985077 | doi-access = free }}</ref>

In the second half of 20th century, substantial contributions and formalizations have been made by Europeans such as [[Jürgen Aschoff]] and [[Colin Pittendrigh]], who pursued different but complementary views on the phenomenon of [[entrainment (chronobiology)|entrainment]] of the circadian system by light (parametric, continuous, tonic, gradual vs. nonparametric, discrete, phasic, instantaneous, respectively<ref>see [http://jbr.sagepub.com/cgi/reprint/15/3/195 this historical article], subscription required</ref>).

;Chronotypes
Humans can have a propensity to be morning people or evening people; these behavioral preferences are called [[chronotype]]s for which there are various assessment questionnaires and biological marker correlations.<ref>{{Cite book|title=The Power of When|last=Breus, PHD|first=Michael|publisher=Little Brown and Company|year=2016|isbn=978-0-316-39126-9}}</ref>

;Mealtimes
There is also a food-entrainable biological clock, which is not confined to the suprachiasmatic nucleus. The location of this clock has been disputed. Working with mice, however, Fuller ''et al.'' concluded that the food-entrainable clock seems to be located in the dorsomedial [[hypothalamus]]. During restricted feeding, it takes over control of such functions as activity timing, increasing the chances of the animal successfully locating food resources.<ref>{{cite journal |last=Fuller |first=Patrick M. |author2=Jun Lu |author3=Clifford B. Saper  |date=2008-05-23 |title=Differential Rescue of Light- and Food-Entrainable Circadian Rhythms |journal=Science |volume=320 |issue=5879 |pages=1074–1077 |pmid=18497298 |doi=10.1126/science.1153277 |bibcode = 2008Sci...320.1074F |pmc=3489954}}</ref>

;Diurnal patterns on the Internet
In 2018 a study published in PLoS ONE showed how 73 psychometric indicators measured on Twitter Content follow a diurnal pattern.
<ref>{{cite journal |last=Dzogang |first=Fabon |author2=Stafford Lightman |author3= Nello Cristianini  |date=2018-06-20 |title= Diurnal Variation of Psychometric Indicators in Twitter Content |journal= PLOS ONE |volume=13 |issue=6 |pages=e0197002 |doi= 10.1371/journal.pone.0197002 |pmid=29924814 |pmc=6010242 |bibcode=2018PLoSO..1397002D |doi-access=free }}</ref> 
A followup study appeared on Chronobiology International in 2021 showed that these patterns were not disrupted by the 2020 UK lockdown.<ref>{{cite journal |last=Wang |first=Sheng |author2=Stafford Lightman |author3= Nello Cristianini  |date=2021-06-17 |title= Effect of the lockdown on diurnal patterns of emotion expression in Twitter |journal= Chronobiology International |volume=38 |issue=11 |pages=1591–1610 |doi= 10.1080/07420528.2021.1937198|pmid=34134583 |s2cid=235462661 |url=https://research-information.bris.ac.uk/en/publications/d064a56f-5da0-4210-95dc-f575acdf3b68 |hdl=1983/d064a56f-5da0-4210-95dc-f575acdf3b68 |hdl-access=free }}</ref>

;Modulators of circadian rhythms
In 2021, scientists reported the development of a light-responsive days-lasting modulator of circadian rhythms of tissues [[Casein kinase 1#Circadian rhythm|via Ck1 inhibition]]. Such modulators may be useful for chronobiology research and repair of organs that are "out of sync".<ref>{{cite news |title=Resetting the biological clock by flipping a switch |url=https://phys.org/news/2021-05-resetting-biological-clock-flipping.html |access-date=14 June 2021 |work=phys.org |language=en}}</ref><ref>{{cite journal |last1=Kolarski |first1=Dušan |last2=Miró-Vinyals |first2=Carla |last3=Sugiyama |first3=Akiko |last4=Srivastava |first4=Ashutosh |last5=Ono |first5=Daisuke |last6=Nagai |first6=Yoshiko |last7=Iida |first7=Mui |last8=Itami |first8=Kenichiro |last9=Tama |first9=Florence |last10=Szymanski |first10=Wiktor |last11=Hirota |first11=Tsuyoshi |last12=Feringa |first12=Ben L. |title=Reversible modulation of circadian time with chronophotopharmacology |journal=Nature Communications |date=2021-05-26 |volume=12 |issue=1 |pages=3164 |doi=10.1038/s41467-021-23301-x |pmid=34039965 |pmc=8155176 |bibcode=2021NatCo..12.3164K |language=en |issn=2041-1723}} [[File:CC-BY icon.svg|50px]] Available under [https://creativecommons.org/licenses/by/4.0/ CC BY 4.0].</ref>