The Journal of Comparative Physiology celebrates its 100th anniversary this year. Founded in 1924 as "Zeitschrift für vergleichende Physiologie" by Karl von Frisch and Alfred Kühn, the journal adopted English as its language in 1977, becoming the "Journal of Comparative Physiology." In 1984, it split into Part A and Part B, focusing respectively on neurophysiology and sensory physiology, and metabolic physiology and environmental adaptation. This year, we also commemorate the 40th anniversaries of both parts.

Despite significant advancements, there remain substantial gaps in our understanding of physiological processes, particularly in the area of sleep—a vital yet poorly understood phenomenon in both animals and humans.

To celebrate the journal's longevity and advance our knowledge of sleep, Editor in Chief Gerhard Heldmaier commissioned a special issue on the "Comparative Physiology of Sleep and Circadian Rhythms." Edited by Vladyslav Vyazovskiy and Stuart Peirson from the University of Oxford, this special issue provides an extensive overview of sleep occurrence and its comparative physiology.

The special issue features 13 articles, including a celebratory editorial, offering new insights into sleep patterns and neurochemistry across a variety of animal species, including hamsters, mice, rats, seals, cichlids, zebrafish, wildebeest, and flatworms.

You can read the content of the Special Issue here.