Influence of Environmental Factors on Sleep Quality: Analyzing Light Exposure and Sleep Duration with Smartwatch Data

Artificial lighting significantly influences circadian rhythms and sleep quality. This case study investigates the impact of environmental factors including temperature, relative humidity, CO₂ concentration, total volatile organic compounds (TVOC) and exposure to different light spectra on light sleep duration in a single subject. Sleep data were collected using a Xiaomi Mi Band 6 smart wristband, while environmental parameters were monitored with a custom Arduino-based sensor system. The results indicate that the optimal temperature for light sleep ranges between 17 and 21 C, with the longest light sleep recorded at approximately 18 C. Humidity, CO₂ and TVOC levels showed no significant effect on light sleep duration. Regarding light exposure, the longest light sleep occurred in complete darkness, while the shortest was observed under red light. However, the light spectrum did not show a consistent impact on light sleep duration, suggesting that its influence may be more pronounced in deeper sleep stages. Since this is a single-subject study, the findings are preliminary and not generalizable. Further research involving a larger sample size is needed to validate these observations and better understand individual differences in sleep responses to environmental conditions.