Introduction
 Humans, as social beings, cannot live independently and without the need for society. A solitary human always feels incomplete. Loneliness is a form of social separation and a discomforting feeling arising from our unmet need for perceived social connection. Thus, it can be described as a type of social pain. In other words, it is a painful feeling of being cut off and separated from others, an unpleasant experience that emerges in response to quantitative and qualitative deficiencies in social relationships. Loneliness, described as the "hidden epidemic of the 21st century," has become a fundamental challenge in urban societies. Despite its multifaceted consequences, there is a research gap in the systematic analysis of the role of urban planning in exacerbating loneliness. 
Methodology
This study, with an interdisciplinary approach, comprehensively analyzes the effective indicators in this context. The study is applied in terms of its objective and descriptive-analytical with a mixed method approach in terms of its method. The statistical population of the research consists of experts in psychology, sociology, social sciences, architecture, urban planning, and social psychology. The sample size was determined to be 100 people using the G*Power software, and the questionnaire was distributed among the experts using the snowball sampling method. The validity of the tool was confirmed by expert judgment. Data collection was carried out in the literature review, background, and research indicators sections using the library method, and in the measurement and evaluation of indicators section using the field method and questionnaire. The data were analyzed using the Friedman test, one-sample t-test, and correlation in the SPSS software.
Result and discussion 
The Friedman test results indicated that inadequate access to green spaces (rank 1), social places (rank 2), and low social participation (rank 3) were the most important factors in creating and exacerbating urban loneliness. Additionally, factors such as limited access to recreational spaces, lack of natural elements in the urban environment, and frequent changes in the urban fabric that weaken place identity were recognized as other influencing indicators in exacerbating the loneliness crisis. The one-sample t-test results showed that access to public (2.27) and social (2.11) spaces had the most significant impact on the feeling of loneliness in urban environments. This finding highlights the importance of interactive spaces in reducing the feeling of loneliness. Furthermore, low social participation (2.02) and inadequate access to recreational spaces (1.56) were identified as other influential factors. A significant relationship between environmental-natural factors and loneliness was also observed; the lack of natural sounds (1.46), absence of nature views from windows (1.15), and shortage of green spaces (1.03) were associated with increased feelings of loneliness. Cultural-identity factors, such as the loss of memory due to continuous changes in the urban environment (1.28) and socio-economic classifications (1.06), also play a role in this phenomenon. In contrast, purely physical indicators like population density (0.03), facade quality (0.08), and building height proportion (0.05) had little impact on the feeling of loneliness. The comparison of Friedman and one-sample t-test results shows significant alignment. A strong positive correlation confirms that the results of both tests are closely related, with almost 91% of changes in the ranking of indicators in one test explainable by changes in the other. This strong correlation indicates that both statistical methods provide similar results in evaluating the relative importance of indicators. The findings of this study show that the indicators influencing the creation or exacerbation of loneliness in urban planning are divided into eight main clusters. These clusters include access to and quality of public and social spaces, social participation and interactions, human-nature connection, urban culture and identity, built environment quality and visual aspects, housing physical characteristics, residential environment features, and access to daily services and amenities. Each of these clusters plays a significant role in reducing or exacerbating the feeling of loneliness in urban spaces, and emphasizing the improvement of these factors can enhance urban life quality and reduce loneliness. Comparing this research's results with other studies shows that most studies have examined loneliness from individual and emotional aspects, while a comprehensive study on the impact of urban planning indicators on loneliness does not exist. The findings on nature indicators, access to services, and social places are aligned with studies like those by Lowell Sachs et al., Moore et al., and Ji Hee Lee and Tak Hon Tan. Loneliness in contemporary cities forms from the interaction of physical, social, cultural, and environmental factors. This phenomenon is influenced by three main layers: physical-spatial (including public spaces and housing quality), socio-cultural (citizen participation and collective activities), and environmental-ecological (connection with nature and natural elements). The combination of these factors can lead to an increase or decrease in the feeling of loneliness in citizens.
Conclusion 
Urban planning requires an integrated and multi-level approach that simultaneously considers physical, social, and environmental dimensions and is based on nature-oriented and human-oriented principles. This approach should include strategies such as creating an integrated network of public spaces, strengthening social infrastructure, integrating natural elements into urban design, and preserving cultural heritage.