melatonin | definition

hormone secreted by the endocrine gland that serves as an important regulator of the sleepwake cycle


Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020). Psychology 2e. Houston, Texas: OpenStax. Access for free at


Research Article: Melatonin Immunoreactivity in Malignant Small Intestinal Neuroendocrine Tumours

Date Published: October 13, 2016 Publisher: Public Library of Science Author(s): Fanny Söderquist, Eva Tiensuu Janson, Annica J. Rasmusson, Abir Ali, Mats Stridsberg, Janet L. Cunningham, Andrzej T Slominski. Abstract: Small intestinal neuroendocrine tumours (SI-NETs) are derived from enterochromaffin cells. After demonstrating melatonin in enterochromaffin cells, we hypothesized that SI-NETs may express and secrete … Continue reading

Research Article: Individual Differences in the Amount and Timing of Salivary Melatonin Secretion

Date Published: August 26, 2008 Publisher: Public Library of Science Author(s): Helen J. Burgess, Louis F. Fogg, Shin Yamazaki. Abstract: The aim of this study was to examine individual differences in a large sample of complete melatonin profiles not suppressed by light and search for possible associations between the amount and timing of melatonin secretion … Continue reading

Research Article: Human Gastroenteropancreatic Expression of Melatonin and Its Receptors MT1 and MT2

Date Published: March 30, 2015 Publisher: Public Library of Science Author(s): Fanny Söderquist, Per M. Hellström, Janet L. Cunningham, Andrzej T Slominski. Abstract: The largest source of melatonin, according to animal studies, is the gastrointestinal (GI) tract but this is not yet thoroughly characterized in humans. This study aims to map the expression of … Continue reading

Research Article: Meta-Analysis: Melatonin for the Treatment of Primary Sleep Disorders

Date Published: May 17, 2013 Publisher: Public Library of Science Author(s): Eduardo Ferracioli-Oda, Ahmad Qawasmi, Michael H. Bloch, Andrej A. Romanovsky. Abstract: To investigate the efficacy of melatonin compared to placebo in improving sleep parameters in patients with primary sleep disorders. PubMed was searched for randomized, placebo-controlled trials examining the effects of melatonin for the … Continue reading

Research Article: Salivary Melatonin in Relation to Depressive Symptom Severity in Young Adults

Date Published: April 4, 2016 Publisher: Public Library of Science Author(s): Isak Sundberg, Mia Ramklint, Mats Stridsberg, Fotios C. Papadopoulos, Lisa Ekselius, Janet L. Cunningham, Peter John McKenna. Abstract: Reduced levels of melatonin have been associated with severe depression. The aim was to investigate the correlation between salivary melatonin and dimensional measures of depressive … Continue reading

Research Article: Melatonin Signaling Modulates Clock Genes Expression in the Mouse Retina

Date Published: September 9, 2014 Publisher: Public Library of Science Author(s): Susumu Hiragaki, Kenkichi Baba, Elise Coulson, Stefanie Kunst, Rainer Spessert, Gianluca Tosini, Shin Yamazaki. Abstract: Previous studies have shown that retinal melatonin plays an important role in the regulation of retinal daily and circadian rhythms. Melatonin exerts its influence by binding to G-protein … Continue reading

Research Article: Long-Lasting Priming of Endothelial Cells by Plasma Melatonin Levels

Date Published: November 12, 2010 Publisher: Public Library of Science Author(s): Eduardo Koji Tamura, Pedro Augusto Fernandes, Marina Marçola, Sanseray da Silveira Cruz-Machado, Regina Pekelmann Markus, Harald H. H. W. Schmidt. Abstract: Endothelial cells are of great interest for cell therapy and tissue engineering. Understanding the heterogeneity among cell lines originating from different sources and … Continue reading

Research Article: Melatonin Induces Follicle Maturation in Danio rerio

Date Published: May 25, 2011 Publisher: Public Library of Science Author(s): Oliana Carnevali, Giorgia Gioacchini, Francesca Maradonna, Ike Olivotto, Beatrice Migliarini, Immo A. Hansen. Abstract: Most organisms modulate their reproductive activity responding to day length by the nocturnal release of melatonin by the pineal gland. This hormone is also responsible for synchronizing reproduction with specific … Continue reading

Research Article: Melatonin-Mediated Cytoprotection against Hyperglycemic Injury in Müller Cells

Date Published: December 4, 2012 Publisher: Public Library of Science Author(s): Tingting Jiang, Qing Chang, Zhenyang Zhao, Saimei Yan, Ling Wang, Jiyang Cai, Gezhi Xu, Florian Sennlaub. Abstract: Oxidative stress is a contributing factor to the development and progression of diabetic retinopathy, a leading cause of blindness in people at working age worldwide. Recent studies … Continue reading