The sleep maths: A strong correlation between more daytime light and better night-time sleep

Abstract

Lighting for workplaces and schools is typically specified to meet the needs of the visual system without sufficient regard to the lighting characteristics that are required by the human circadian system. In 2020, many workers and students were compelled by the COVID-19 pandemic to work and study from home, where light levels are typically even lower than those found in most schools and workplaces. Using online surveys, this study sought to quantify potential changes in daytime light exposures resulting from teleworking or self-isolating at home and how those changes might have affected self-reported sleep quality, psychological health and emotional health. The first survey was administered in early May 2020, and the second survey was administered in September 2020. In broad terms, our analysis indicates that the greater the amount of light one is exposed to during the day (either in the home or outdoors), the better the self-reported sleep outcomes. Stress and mood were also correlated with greater self-reported daytime light exposures. The results suggest that spending one to two hours outdoors or staying in a bright to very bright room indoors may improve night-time sleep. These results have important implications for daytime lighting in homes, offices and schools.