Long-term Spectral Light Analysis
Effect of Lighting Conditions on Health and Well-Being
Project Justification
Artificial lighting has a significant impact on human well–being and sleep regulation. However, the extent to which natural light exposure influences health and emotional states remains a subject of ongoing scientific discussion. Key parameters such as light intensity, angle of exposure, and spectral composition (light color) are believed to play a central role in mediating these mood- and health-related effects.
This study aims to systematically map and compare these light-related parameters over an extended period at two distinct geographical locations – one in the Mediterranean region and one in Central Europe. By capturing long-term exposure patterns, the study seeks to better understand the chronobiological relevance of naturally occurring light conditions and their implications for sleep quality, circadian stability, and psychological well-being.
Our Approach
Data collection was conducted over a period of nine months at two geographically distinct sites: Santiago do Cacém (Portugal) and Datteln (Germany). At both locations, a comprehensive set of chronobiologically relevant lighting parameters was continuously monitored. These included:
– Total light intensity (illuminance)
– Irradiance ratio with a focus on blue light components
– Ultraviolet (UV) spectral fractions
– Mood lighting characteristics
– Daytime-dependent blue-to-red spectral ratio
By capturing and analyzing these variables across varying seasonal and atmospheric conditions, the study aims to provide valuable insights into the natural variation of light exposure and its potential impact on human physiology and emotional states in different climatic regions.
Significant differences in the proportions of the color components of higher intensities can be seen.
Insights and Outcomes
Analyses revealed significant differences in light characteristics between the two study locations. The data collected in Santiago do Cacém (Portugal) indicated several mood- and health-related advantages compared to Datteln (Germany).
Specifically, the Portuguese site exhibited a slower seasonal decline in daylight duration, higher overall illuminance (lux intensity), greater spectral irradiance, and a more favorable blue-to-red light ratio throughout the day. These environmental lighting conditions are associated with enhanced mood regulation, improved circadian alignment, and better overall sleep quality.
In contrast, the data suggest that individuals living in Central European climates – such as Germany – may be at greater risk for seasonal affective disorder (SAD), Vitamin D deficiency, impaired sleep quality, and increased circadian disruption during the darker months of the year. These findings highlight the relevance of location-specific lighting strategies to mitigate adverse seasonal health effects and support circadian stability.
Winter days in Portugal have an average light intensity of 15,000 lux, three times the intensity of an average winter day in Germany.
Related Projects
Simulating long-haul flights in a high fidelity cabin mockup
Enhance sleep quality and well-being in hotels and spas
Long-term measurement of spectral light conditions in Portuguese rehab settings
Long-term psychoneuro-endocrinologic evaluation of a chronobiologically adapted light system