The circadian clock in modern society

Since the start of life on Earth, virtually every species evolved under a 24-hour light-dark cycle, giving rise to an internal biological clock that is remarkably well-conserved throughout a wide range of plant and animal species. In most species, specialised photoreceptors respond to specific wavelengths and intensities of light, serving as the principal external signal to the internal clock. Importantly, biological rhythms are genetically encoded according to very similar principles among species. In general, a strong rhythm promotes health, while a disruption of rhythms can exacerbate or even cause a wide range of mental and physical diseases. Since the introduction of shift work in the 1850s, transatlantic flights in the 1960s, and by the pervasive use of artificial light at night, we have been increasingly ignoring our biological clock, and those of the organisms in the natural environment. Due to the high population density, extensive industrialisation, and the widespread presence of greenhouses, the Netherlands is one of the most light-polluted countries in the world. This has dire consequences for our clocks and for health. Preserving our clock has drawn growing interest in society, reflected by the many questions posed via the NWA with respect to: i) optimising our daily schedule in order to improve our health, mood, and sleep quality, particularly among adolescents and the elderly, ii) optimising the efficacy of medical treatments, improving clock function in patients, and developing clock-enhancing tools, and iii) protecting our fragile ecosystem and maintaining our planetâ??s rich biodiversity. In this project, a unique consortium of scientists, clinicians, local governments, and other societal partners will undertake an ambitious but attainable project designed to directly address these key issues, ultimately benefiting not only our own health and well-being, but also the world around us.