Seasonal influence of a roadside tree belt on sleep disturbance in Tomakomai, Japan

Socio-acoustic surveys were conducted across four seasons at three sites in Tomakomai, Japan. At Site A, the south façades of the surveyed detached houses faced a tree belt; at Site B, the south façades faced an arterial road; and at Site C, the north façades faced the road. The percentage of respondents who were at least very sleep disturbed (%VSD) was significantly lower at Site A than at Site B. This suggests that the presence of green space significantly reduced sleep disturbance-an effect that was larger in summer than in the other seasons-and is consistent with previous findings. The location of the tree belt between the road and the houses may reduce residents' stress and improve sleep quality. This improvement may be further enhanced by the moderating effects of the tree belt on the thermal environment and its reduction of air pollution, particularly in summer when people open bedroom windows more frequently than in other seasons.