A multidisciplinary perspective on the effects of global climate change on light exposure and health

• Cities and buildings adapt to heat waves by increasingly using solar protections and shading devices. Shifting the work schedule towards the night is also a growing strategy to avoid high daytime temperatures. • Buildings and shading systems should be designed using climate-based daylighting metrics to better prevent glare and overheating. • The individual exposure to light and access to clear unobstructed outside views are profoundly compromised during heat waves. • Disruptions in the circadian rhythm and the sleep-wake cycle are expected, worsening the health effects of high temperatures. • Electric lighting systems will be used for longer periods, increasing the lighting energy consumption beyond the values prescribed by current standards and regulations. Electric lighting systems will have to deliver a better quality of light to provide circadian entrainment and minimize adverse health effects. Global climate change is affecting our exposure to daylight and our use of lighting systems. Considering the increasingly frequent heat waves, the time spent indoors is predicted to increase dramatically. With more efficient solar shading, the available daylight in buildings may be reduced, possibly resulting in a deficiency in the necessary light for health. The growing use of shiftwork or nightwork during heat waves is also responsible for circadian misalignment and sleep debt. Under these conditions, lighting systems need to be adapted to promote wakefulness and the proper entrainment of the circadian timing system.