Professor Josephine Arendt

Emeritus Professor of Endocrinology, Director (ex), Centre for Chronobiology


My qualifications

BSc      Biochemistry (Hons) University College London, 1959-1962

PhD     Biochemistry    University of London    1962-1965. Metabolism of Tryptophan and its Indolic Analogues. Languages: English and French.

Affiliations and memberships

Royal College of Pathology

Royal Society of Medicine

Royal Society of Biology

The Society for Endocrinology

The European Pineal Society now the European Biological Rhythms Society

Society for the Study of Fertility.

Society for Research into Biological Rhythms

Society for Light Treatment and Biological Rhythms

European Sleep Research Society

British Sleep Research Society

British Neuroendocrine Society

Committees (previous and current)   
World Federation of Societies for Chronobiology (ex Council Member).

The European Biological Rhythms Society (Life Member of Council).

Society for Light Treatment and Biological Rhythms (Founder Member, ex Board Member).

Society for Research on Biological Rhythms (ex Board Member at Large)

NRPB Advisory Group on Non-ionising Radiation (melatonin sub-group).

Scientific Committee on Antarctic Research, Expert Group on Human Biology and Medicine (Associate Member).

Evaluator: CNRS, France, QinetiQ subgroup human factors (2004)

Advisor, UK Parliamentary Office of Science and Technology (2005)

MRC Advisory Group on breast cancer & shiftwork (2005)

IARC (WHO) Monograph Group on Shiftwork and Cancer (2007-2011)

Business, industry and community links

Founder and director of Stockgrand Ltd a University company exploiting technological expertise in melatonin and biological rhythms to support research, especially funding for PhD students.


Research interests



Marta Garaulet, Jingyi Qian, Jose C. Florez, Josephine Arendt, Richa Saxena, Frank A. J. L. Scheer (2020)Melatonin Effects on Glucose Metabolism: Time To Unlock the Controversy, In: Trends in endocrinology and metabolism31(3)pp. 192-204 Elsevier

The past decade has witnessed a revival of interest in the hormone melatonin, partly attributable to the discovery that genetic variation in MTNR1B - the melatonin receptor gene - is a risk factor for impaired fasting glucose and type 2 diabetes (T2D). Despite intensive investigation, there is considerable confusion and seemingly conflicting data on the metabolic effects of melatonin and MTNR1B variation, and disagreement on whether melatonin is metabolically beneficial or deleterious, a crucial issue for melatonin agonist/antagonist drug development and dosing time. We provide a conceptual framework - anchored in the dimension of 'time' - to reconcile paradoxical findings in the literature. We propose that the relative timing between elevated melatonin concentrations and glycemic challenge should be considered to better understand the mechanisms and therapeutic opportunities of melatonin signaling in glycemic health and disease.

Jingyi Qian, Christopher J Morris, Andrew J K Phillips, Peng Li, Shadab A Rahman, Wei Wang, Kun Hu, Josephine Arendt, Charles A Czeisler, Frank A J L Scheer (2022)Unanticipated daytime melatonin secretion on a simulated night shift schedule generates a distinctive 24-h melatonin rhythm with antiphasic daytime and nighttime peaks, In: Journal of pineal research72(3)e12791pp. e12791-n/a

The daily rhythm of plasma melatonin concentrations is typically unimodal, with one broad peak during the circadian night and near-undetectable levels during the circadian day. Light at night acutely suppresses melatonin secretion and phase shifts its endogenous circadian rhythm. In contrast, exposure to darkness during the circadian day has not generally been reported to increase circulating melatonin concentrations acutely. Here, in a highly-controlled simulated night shift protocol with 12-h inverted behavioral/environmental cycles, we unexpectedly found that circulating melatonin levels were significantly increased during daytime sleep (p 

Steven W. Lockley, Josephine Arendt, Debra J. Skene (2017)Visual Impairment and Circadian Rhythm Sleep Disorders, In: Reference Module in Neuroscience and Biobehavioral Psychologypp. 428-437 Elsevier Inc

Many aspects of human physiology, metabolism, and behavior are dominated by 24-h circadian rhythms including the sleep–wake cycle, alertness and performance patterns, and some hormones. These rhythms are spontaneously generated by an internal circadian clock in the brain and daily light exposure to the eyes synchronizes the clock with the external environment. Most blind people with no perception of light, however, experience continual circadian desynchrony through a failure of light information to reach the circadian pacemaker, resulting in non-24-h sleep–wake disorder. Daily melatonin administration, which provides a replacement synchronizing daily “time cue,” is a promising therapeutic strategy to treat this disorder.

Tracey L. Sletten, Jason P. Sullivan, Josephine Arendt, Lawrence A. Palinkas, Laura K. Barger, Lloyd Fletcher, Malcolm Arnold, Jan Wallace, Clive Strauss, Richard J. S. Baker, Kate Kloza, David J. Kennaway, Shantha M. W. Rajaratnam, Jeff Ayton, Steven W. Lockley (2022)The role of circadian phase in sleep and performance during Antarctic winter expeditions, In: Journal of pineal research73(2)e12817pp. e12817-n/a

Abstract The Antarctic environment presents an extreme variation in the natural light‐dark cycle which can cause variability in the alignment of the circadian pacemaker with the timing of sleep, causing sleep disruption, and impaired mood and performance. This study assessed the incidence of circadian misalignment and the consequences for sleep, cognition, and psychological health in 51 over‐wintering Antarctic expeditioners (45.6 ± 11.9 years) who completed daily sleep diaries, and monthly performance tests and psychological health questionnaires for 6 months. Circadian phase was assessed via monthly 48‐h urine collections to assess the 6‐sulphatoxymelatonin (aMT6s) rhythm. Although the average individual sleep duration was 7.2 ± 0.8 h, there was substantial sleep deficiency with 41.4% of sleep episodes

Additional publications