The research project “ChronoBlue – Light, Performance, Quality of Life”, funded by the Peter Beate Heller-Stiftung im Stifterverband, investigates how the targeted use of blue light can influence the human body clock in order to sustainably optimise physical and cognitive performance, well-being and recovery across the course of the day. The project operates in the field of tension between an evolutionarily shaped circadian system and the demands of a modern 24/7 society that increasingly challenges natural day-night rhythms. So-called “social jetlag” – a shift between our genetically anchored internal time structure and a socially imposed schedule – is widespread and associated with an increased risk of cancer, metabolic disease, cardiovascular disease and mental illness. The aim of the project is therefore to deliberately counteract this disruption of chronobiological processes.
External time cues are central to that counteraction. The strongest external zeitgeber of the circadian rhythm is light, and short-wavelength blue light in particular. It acts through melanopsin-containing retinal ganglion cells on the suprachiasmatic nucleus in the hypothalamus – the central pacemaker of our body clock, which coordinates the sleep-wake rhythm, hormone release, body temperature and time-of-day dependent performance, among other things.
ChronoBlue works at this intersection of light, body clock and health, and understands blue light as a controllable element of a “therapeutic landscape” that can simulate natural lighting conditions where access to forest, nature and daylight is limited. The project thus fits into the funding programme “Gesunde Orte – Therapeutische Landschaften” (Healthy Places – Therapeutic Landscapes) and examines the temporal dimension of health-promoting lighting environments – that is, the question of when which light is beneficial to health – and makes these findings usable in everyday life.
In the funded variant of the project, a cohort of elite athletes is studied in cooperation with the German Swimming Federation (DSV). In elite sport even small differences in physical and cognitive performance can decide a competition, which gives factors such as time of day, individual chronotype and (social) jetlag particular weight. The aim is to align each athlete's individual performance peak with the demands of training and competition.
Building on an extensive baseline assessment of chronotype, sleep quality, physiological stress markers, core body temperature and athletic performance, blue light interventions are delivered by means of special glasses temples during chronobiologically sensitive windows (for example around dawn and dusk) in order to shift the circadian phase in a targeted way. The cooperative project is accompanied by a controlled laboratory study that makes the effects of this phase adjustment quantifiable in biochemical terms as well.
Although the project currently studies an elite sport cohort, its wider social ambition remains explicit: the results are in principle transferable to broader groups of the population. The findings gained in sport are to be translated into evidence-based recommendations for people in urban environments, for shift workers, for older people and for those in care facilities. The vision of the project is a kind of “light compass” for the body clock, one that helps many people match their lighting environment better to health, well-being and performance.