## 5 Conclusions and Discussion  
Effectively applying GBD to the analysis of new socio-economic phenomena can provide a more comprehensive, in-depth understanding of their essence and mechanisms. The NTE is an important form of expansion in urban commercial activities. It is also one of the primary phenomena facilitated by the Chinese government to promote urban consumption and capital flow. We applied POI data and NTL RSD to analyze the spatial features and mechanisms of the NTE in the YRD from the perspective of urban geography, expecting to provide a valuable reference for urban commercial planning. The NTEs of cities in the YRD have core-peripheral features. Shanghai occupies the core position. The sub-core cities are provincial-level cities such as Hefei, Nanjing, Wuxi, Suzhou, Hangzhou, Ningbo, and Hangzhou. Yancheng, Yangzhou, Taizhou, Nantong, Zhenjiang, Changzhou, Jiaxing, Shaoxing, Taizhou, and Jinhua are in the sub-peripheral position. The most peripheral regions are Anqing, Tongling, Ma'anshan, Xuancheng, and Chizhou. The spatial structure spreads in the northwest-southeast direction, possibly due to the imbalance of nighttime infrastructure services, especially transportation infrastructure. Government policies, resident consumption levels, urban industrial structures, and economic growth levels are the main factors affecting the regional NTE. Further, the interaction of these factors is more effective for the expansion of nighttime economic activities than a single condition. Given the differences in urban spaces, building nighttime urban economic clusters and activity hotspots by classification is of great value. Examples include building a first-level nighttime economic agglomeration space in an urban comprehensive center with higher nuclear density, building a second-level nighttime economic agglomeration space grounded in the urban district center in an area with lower nuclear density, and finally building a third-level nighttime economic agglomeration space in township, community, and business district centers. Nighttime economic activities should be created that can highlight the characteristics of culture and art in tourist attractions as well as cultural and art centers. In addition, commercial catering activities can be implemented that can hold business banquets in office areas. Moreover, nighttime economic activities can be arranged that focus on community public services in public spaces where crowds gather. In accordance with the spatial pattern of the nighttime economy in the Yangtze River Delta, it is essential to strategically coordinate the supply and demand relationship of corresponding service facilities. The proportion of relative deficit areas for service facilities related to the nighttime economy, including dining, accommodation, transportation, tourism, entertainment, and shopping, is higher than that of relative surplus areas. Specifically, there is a relative shortage in the supply of nighttime economic service facilities, with dining facilities having a relatively balanced construction. Shopping service facilities have relatively sufficient construction, while there is still a need for improvement in the construction of transportation infrastructure. Therefore, it is necessary to continue leveraging the radiating and driving role of nighttime economic activity hotspots in surrounding areas. This involves strengthening the infrastructure development in these hotspots and addressing the relative deficit phenomenon in service facilities. Creating distinctive neighborhoods and nighttime cultural tourism projects in the peripheral areas of the Yangtze River Delta can attract tourists to participate in nighttime economic activities, achieving the guidance and dispersion of nighttime pedestrian flow. Urban public transportation services should adjust their operating hours according to the anticipated scale of nighttime economic activities, considering appropriately extending operation times.