Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

Research output: Contribution to journalArticleScientificpeer-review


  • Maja Grubisic
  • Abraham Haim
  • Pramod Bhusal
  • Davide M. Dominoni
  • Katharina M.A. Gabriel
  • Andreas Jechow
  • Franziska Kupprat
  • Amit Lerner
  • Paul Marchant
  • William Riley
  • Katarína Stebelová
  • Roy H. A. Van Grunsven
  • Michal Zeman
  • Abed Zubidat
  • Franz Hölker

Research units

  • Leibniz-Institute of Freshwater Ecology and Inland Fisheries
  • Free University of Berlin
  • University of Haifa
  • University of Glasgow
  • University of Würzburg
  • Helmholtz Centre Potsdam - German Research Centre for Geosciences
  • Israel Oceanographic and Limnological Research Institute
  • Leeds Beckett University
  • University of Leeds
  • Centre for the Environment Fisheries and Aquaculture Science
  • Comenius University
  • Dutch Butterfly Conservation


Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies. However, ALAN and resulting light pollution can cause unintended physiological consequences. In vertebrates, production of melatonin—the “hormone of darkness” and a key player in circadian regulation—can be suppressed by ALAN. In this paper, we provide an overview of research on melatonin and ALAN in vertebrates. We discuss how ALAN disrupts natural photic environments, its effect on melatonin and circadian rhythms, and different photoreceptor systems across vertebrate taxa. We then present the results of a systematic review in which we identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking. No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown. Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems.


Original languageEnglish
Article number6400
Number of pages51
Publication statusPublished - 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • ALAN, Artificial light at night, Biological rhythm, Circadian rhythm, Melatonin

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