Residential greenspace exposure, particularly green window-views, is associated with improved sleep quality among older adults: Evidence from a high-density city

Abstract

Preliminary evidence suggests a potential link between greenspace exposure and better sleep quality. Here we aimed to investigate the specific associations between residential greenspace exposure, green-window views, and sleep quality among older adults and determine whether these associations were mediated through mitigation (i.e., perceived noise annoyance, air pollution, and artificial light pollution) and restoration (i.e., psychological stress) pathways. A total of 1007 older adults with an average age >70 years were recruited from 40 residential communities in the Old City District of Nanjing, China. We developed a set of fine-grained greenspace exposure indices based on 3D point cloud data derived from unmanned aerial vehicle photogrammetry, incorporating vegetation coverage and green volume ratio at the community level and green window ratio at the individual level. Sleep quality was assessed using the Pittsburgh Sleep Quality Index. We examined the complex interrelationships between residential greenspace exposure, environmental stressors (air pollution, artificial light pollution, and noise), perceived mental stress, and sleep quality using multilevel linear regression models. The results suggested the following: (1) Vegetation coverage, green volume ratio, and green window ratio were significantly associated with sleep quality in older adults. (2) The green window ratio was more strongly associated with improved sleep quality than other greenspace exposure metrics. (3) These associations may be partially explained by noise mitigation and mental stress reduction. In conclusion, it seems advantageous to consider immediate residential greenspace, particularly through green-window views, as part of the interventions aimed at supporting sleep quality improvement among older adults.