Since the dawn of life on Earth, virtually every organism has been exposed to a daily light-dark cycle. This cycle has led to the evolution of a biological clock that produces a circadian rhythm of approximately 24 hours in all physiological processes, including sleep-wake behaviour, metabolism, hormone release, reproduction, and gene expression. These rhythms allow organisms to adapt to and anticipate cyclic environmental changes caused by the daily rotation of the Earth on its axis and its yearly orbit around the Sun. Because the biological clock is so deeply ingrained in our physiology, it is intertwined with many aspects of our daily lives. The mammalian biological clock consists of thousands of cellular oscillators located deep in the brain that are genetically programmed to generate an intrinsic rhythm. Under normal conditions, these clock cells work in synchrony to produce a bona fide rhythm that serves as a functional 24-hour pacemaker for both brain and body. When synchronisation between these cells is weakened (for example due to shift work, aging, disease, etc.), the resulting rhythms are also weakened or even absent. Consequently, this leads to the loss of temporal coordination of downstream physiological processes. The timing of light exposure, physical activity, and food intake are important cues for synchronising the biological clock. However, these inputs have drastically – and abruptly - changed in our modern society due to the widespread use of artificial light and the round-the-clock demand for goods and services. Currently, 80% of the world’s population live in areas with a light-polluted night sky and one in five workers in Europe is engaged in some form of shift work. In addition, the world’s population is rapidly aging and increasingly sedentary. Fundamental research has shown that precisely these conditions cause desynchrony among clock cells. Research has shown that circadian disruption is a clear threat to both public health and vulnerable ecosystems. For example, disruptions in the sleep-wake cycle – and the resulting loss of clock strength - can contribute to mental health disorders such as depression, and night shift work increases the risk of a variety of conditions, including type 2 diabetes, certain types of cancer, cardiovascular disease, reproductive issues, and immune dysfunction. In addition, even low levels of light pollution pose a threat to biodiversity ‒ much like global warming and climate change ‒, impacting daily and seasonal rhythms, reproduction, and the functioning of ecological communities.<br/>Overcoming this wide range of challenges requires close collaboration between a variety of complementary disciplines, with each discipline contributing unique expertise regarding the mechanism underlying biological clock function and/or applied research based on the obtained fundamental insights. To achieve this ambitious ‒ yet feasible ‒ goal to protect or even strengthen the clock, we have established the BioClock consortium, in which molecular biologists, neuroscientists, ecologists, clinicians, psychologists team up with educators, policy makers, local governments, environmental organisations, industry, and engaged citizens in order to capitalise on results obtained from basic research on the biological clock, thereby promoting health, quality of life, and biodiversity.