Editing Jet lag (section)

===Melatonin administration===
Melatonin, a hormone secreted by the [[pineal gland]] in response to darkness, serves as a biological signal of night. In contrast to light, which suppresses melatonin and delays sleep onset, exogenous melatonin can phase-shift the circadian clock by mimicking nighttime, making it an effective [[Chronopharmacology|chronopharmacological]] agent for realigning circadian rhythms.<ref>{{cite journal |last1=Lewy |first1=Alfred J. |last2=Bauer |first2=Vance K. |last3=Ahmed |first3=Saeeduddin |last4=Thomas |first4=Katherine H. |last5=Cutler |first5=Neil L. |last6=Singer |first6=Clifford M. |last7=Moffit |first7=Mary T. |last8=Sack |first8=Robert L. |title=The Human Phase Response Curve (Prc) to Melatonin is About 12 Hours out of Phase with the Prc to Light |journal=Chronobiology International |date=January 1998 |volume=15 |issue=1 |pages=71–83 |doi=10.3109/07420529808998671 |pmid=9493716 }}</ref><ref>{{cite journal |last1=Burgess |first1=Helen J. |last2=Revell |first2=Victoria L. |last3=Eastman |first3=Charmane I. |title=A three pulse phase response curve to three milligrams of melatonin in humans |journal=The Journal of Physiology |date=15 January 2008 |volume=586 |issue=2 |pages=639–647 |doi=10.1113/jphysiol.2007.143180 |pmid=18006583 |pmc=2375577 }}</ref> [[Melatonin receptor|Melatonin receptors]] are situated on the [[Suprachiasmatic nucleus|SCN]], which is the anatomical site of the circadian clock.<ref>{{cite journal |last1=Dubocovich |first1=Margarita L. |last2=Benloucif |first2=Susan |last3=Masana |first3=Monica I. |title=Melatonin receptors in the mammalian suprachiasmatic nucleus |journal=Behavioural Brain Research |date=December 1995 |volume=73 |issue=1–2 |pages=141–147 |doi=10.1016/0166-4328(96)00086-1 |pmid=8788492 }}</ref> The results of a few field studies of melatonin administration, monitoring circadian phase, have provided evidence for a correlation between the reduction of jet lag symptoms and the accelerated realignment of the circadian clock.<ref>{{cite journal |last1=Piérard |first1=Christophe |last2=Beaumont |first2=Maurice |last3=Enslen |first3=Marc |last4=Chauffard |first4=Françoise |last5=Tan |first5=Dux-Xian |last6=Reiter |first6=Russel J. |last7=Fontan |first7=Annick |last8=French |first8=Jonathan |last9=Coste |first9=Olivier |last10=Lagarde |first10=Didier |title=Resynchronization of hormonal rhythms after an eastbound flight in humans: effects of slow-release caffeine and melatonin |journal=European Journal of Applied Physiology |date=July 2001 |volume=85 |issue=1–2 |pages=144–150 |doi=10.1007/s004210100418 |pmid=11513308 }}</ref> When administered exogenously, via melatonin pills or melatonin gummies, it can advance or delay the circadian phase and help travelers shift faster and sleep better as they are transitioning between [[Time zone|time zones]].<ref>{{cite web |title = Melatonin for jet lag |url=https://www.timeshifter.com/jet-lag/melatonin-for-jet-lag-type-dose-timing |website =Timeshifter|access-date = 2023-01-03}}</ref>

The efficacy of melatonin depends on the dosage, timing, and individual response to it.<ref>{{Cite journal |last=Arendt |first=Josephine |date=2019-07-16 |title=Melatonin: Countering Chaotic Time Cues |journal=Frontiers in Endocrinology |language=English |volume=10 |page=391 |doi=10.3389/fendo.2019.00391 |doi-access=free |pmid=31379733 |issn=1664-2392|pmc=6646716 }}</ref> If taken early in the evening at the final destination, especially when traveling east, melatonin can help promote sleep and shift the circadian rhythm earlier. Conversely, taking it in the morning instead may delay rhythm and slow adaptation to the new eastern time zone. In addition to the concern around appropriate timing of melatonin use, the legality of the substance in certain countries is also a variable to consider. For athletes, [[anti-doping]] agencies may prohibit or limit its use, preventing them from adapting to new time zones when traveling for games and performing optimally.<ref name="pmid22299812" />