Chronobiology – the scientific study of biological rhythms – is a well established transdisciplinary field with broad implications for general biology and clinical medicine. Its fundamental assumption is that almost all organisms, from single cell algae to humans, are able to monitor the passage of time internally to coordinate physiological functions and behaviors with external temporalities – days, tides, lunar months, and annual seasons. During the first decades of the twentieth century, biologists established rhythmicities for the sleep movement of beans, the migrations and color-changes of crustaceans, and body temperature changes in humans and began to integrate rhythmicity into Darwinian theory. Meanwhile, physician Wilhelm Fliess elaborated principles for an exact biology, a “periods theory” (periodenlehre) based on his clinical observations. The timings he observed in his patients revealed 23-day and 28-day intervals between “critical days” which he attributed to the activity cycles of masculine and feminine “units” of vital matter. By the 1940s a third, 33-day period had been added, and Fliess’ account of the body’s biorhythm was elaborated beyond anything recognizable to biological rhythms researchers as scientific. I argue in this presentation that popularizations of Fliess’ “periods theory” during the 1920s, in the context of philosophical and poetic ruminations about rhythm and the pace of life, reinterpreted his rhythmic intervals as a continual ebbing and flowing of physical, emotional, and intellectual capabilities – the essence of the modern pseudoscience of biorhythm.

Throughout the twentieth century, chronobiologists went to great lengths to find suitable locations, such as caves and bunkers, or even to build laboratories specifically designed to study human circadian rhythms without environmental factors, such as sunlight and social contact. Historiography has dealt with these experiments primarily from the perspective of the scientists, focusing on concepts and technical instruments. However, historians have paid little attention to the test subjects involved. How the volunteers experienced the temporal isolation and what role their perceptions and actions played in the experiments and in the production of chronobiological knowledge has been virtually unknown.

This talk aims to fill this gap by exploring the subject files of the so-called ‘Bunker’ in Erling-Andechs, Bavaria, probably the most important laboratory for human chronobiology for several decades since the 1960s. On the basis of this historical material, the subjects are not understood as passive research objects, but are analysed as participants in a network of actors in which they even became co-experimenters. During the experiment, they pressed buttons for certain events, answered psychological questionnaires, kept diaries about their perception of time, and sometimes even steered chronobiological research in new directions by violating the experimental instructions. In this way, the subjects played a decisive role in shaping the concept of ‘body clocks’ in the 20th century.

In 1977, Stanford sleep researchers LEM Miles, DM Raynal and MA Wilson published a landmark paper on a 28-year-old student who presented with a highly unusual sleep pattern. The researchers determined that J.X. was experiencing a ‘free running’ sleep/wake cycle despite being exposed to all typical time cues, both environmental and social. The authors hypothesized that their subject might actually be suffering from a rare but poorly described syndrome of the sleep wake-cycle, which came to be known as Non-24 Hour Sleep-Wake Disorder (N24SWD).

By the 1970s, profoundly blind people had become firmly established priority subjects for rhythms research. Their inability to perceive light transformed their bodies into natural laboratories with which to study the effects of ‘biological darkness’ on circadian rhythms. Leading figures in chronobiology including Franz Halberg, Charles Czeisler, Mary Lobban, Josephine Arendt, and Rütger Wever all undertook experiments with blind people . This paper will trace the involvement of blind people in circadian rhythms research in the second half of the twentieth century. It will highlight the scientific controversy among early chronobiologists over light as a zeitgeber in humans and the applicability of chronobiology to medical practice. These concerns coalesced around the potential of melatonin to act as a ‘chronobiotic’ – a therapeutic intervention acting on the body clock itself. I hope to illustrate how (some) blind subjects were active research participants – whose concerns for their own sleep played a transformative role in scientific research.

Understanding the history of chronobiology and sleep science is critical to appreciating the profound advancements these fields have made in both scientific discoveries and public health. To map these developments, we utilize a novel method for historiographical and sociological research into contemporary science using Wikipedia’s articles, their text and edit history, references and other data, relying on the platforms’ open, digital and archival features. For this, we identified a corpus of dozens of articles related to this research field, scraped their content and associated metadata, enabling us to track semantic trends, shifts in references, and developments in these fields over the past two decades. Specifically, we will show how Wikipedia's “living text” documented the evolving understanding of the function of sleep, a pivotal area in sleep research, as well as a recent paradigm shift in molecular research on daily timing. Furthermore, our analysis of Wikipedia editors highlights the platform's inclusivity, showcasing a “citizen encyclopedia” of different stripes with contributions from active scientists, individuals with professional experiences, to non-academics and those previously marginalized from encyclopedic efforts.

Wikipedia thus serves as a lens to examine the knowledge transfer, as it extends beyond traditional academic channels and explores the dynamics of information flow in a crowd-sourced environment. Our study further illuminates Wikipedia articles pertaining to chronobiology and sleep medicine, rapidly evolving scientific fields with growing impact on diverse scientific fields and wide-reaching health concerns.