Document Type : Original Article
Authors
1
Ph.D. Candidate in Landscape Architecture, Department of Architecture and Fine Arts, Aras International Campus, University of Tehran, Iran.
2
Faculty of Fine Arts, University of Tehran, Tehran, Iran.
3
Associate Professor, Urban Planning Department, International soore University, Tehran, Iran.
10.22034/rau.2026.2065755.1223
Abstract
This study explores the intricate relationships among environmental conditions, intrinsic biological factors, and the secretion of happiness-related hormones, which collectively shape human mental health and subjective well-being. By integrating insights from neuroscience, environmental psychology, and urban design, the research proposes that the built environment functions not simply as a spatial or infrastructural backdrop, but rather as a neurobiological agent that influences hormonal balance, emotional regulation, and overall psychological resilience. Through an interpretive–comparative analysis of two contrasting urban models—Tehran, a densely populated, car-oriented metropolis, and Copenhagen, a human-centered, pedestrian-oriented urban environment—the study develops a scientifically grounded framework for designing cities that promote happiness, reduce stress, and enhance social connectedness.
Happiness is conceptualized as a multidimensional biopsychosocial construct shaped through continuous interactions between internal determinants—including genetics, temperament, and neurochemical sensitivity—and external environmental stimuli such as light, color, sound, physical accessibility, and social experience. From a biological standpoint, genetic predispositions strongly influence baseline emotional sensitivity. Empirical studies indicate that approximately 30–50% of individual variation in happiness is heritable. Specific genetic polymorphisms contribute to these variations: DRD2 and COMT modulate dopamine pathways involved in reward processing and motivation, while the 5-HTTLPR genotype influences serotonin reuptake, emotional stability, and vulnerability to stress or depression. These intrinsic factors form an individual’s neurobiological foundation, yet their effects are not deterministic; environmental factors can strengthen, compensate for, or undermine genetic predispositions. As a result, the quality of urban environments plays a decisive role in shaping psychological outcomes.
The study focuses on four primary hormones associated with happiness—dopamine, serotonin, oxytocin, and endorphins—and two secondary hormones, melatonin and cortisol, which significantly influence emotional states. Dopamine regulates motivation, pleasure, cognitive engagement, and reward anticipation. Serotonin affects mood balance, sleep regulation, appetite, and emotional processing. Oxytocin enhances trust, empathy, bonding, and prosocial behavior, particularly during positive social interactions. Endorphins act as natural analgesics and stress-reducing agents, released during physical activity, laughter, and sensory enjoyment. Melatonin governs circadian rhythms and sleep quality, while cortisol manages stress responses but can impair emotional stability when chronically elevated. Together, these hormones form the biological infrastructure through which the built environment exerts its psychological influence.
The research identifies four major environmental domains that significantly affect hormonal activity: light and color; sound and acoustic conditions; social interaction and public events; and the interplay between genetics and environmental design. The first domain, light and color, is particularly influential. Exposure to morning light, characterized by bright cool wavelengths, suppresses melatonin levels and stimulates serotonin production, thereby enhancing alertness, motivation, and emotional balance. Conversely, warm evening light promotes melatonin secretion and supports healthy sleep cycles. Color exposure also plays a critical role in emotional modulation. Warm colors such as yellow stimulate positive arousal and dopamine release, strong reds increase excitement and physiological activation, and cool tones like blue encourage calmness and serotonin activity. The effective integration of light and color into architectural and urban design serves as a non-invasive means of promoting psychological well-being.
The second environmental domain—sound—exerts a substantial influence on hormonal regulation. Pleasant natural sounds, melodic music, and controlled acoustic environments elevate dopamine and oxytocin levels while reducing cortisol. In contrast, noise pollution—especially from vehicular traffic, machinery, and crowded urban areas—initiates chronic stress responses, impairs emotional regulation, and contributes to long-term psychological fatigue. Acoustic planning in urban design is important for mental health because 432 Hz sound frequencies may calm physiological responses, potentially aligning biological rhythms and reducing stress.
The third domain involves social interaction and the structure of public space. Human beings are inherently social, and environments that facilitate spontaneous encounters, accessible gathering spaces, and community events significantly stimulate oxytocin and serotonin pathways. Parks, public squares, mixed-use developments, and pedestrian-friendly streets foster a sense of belonging, trust, and emotional stability. In contrast, environments dominated by vehicles, extensive travel times, and limited public space restrict social opportunities, weaken community ties, and reduce hormonal conditions associated with well-being. The design of social space, therefore, becomes a critical determinant of urban mental health.
Methodologically, the study employs an interpretive–comparative approach, synthesizing scientific literature on environmental psychology and neuroscience with observational and contextual analysis of Tehran and Copenhagen. Tehran exemplifies an environment where chronic exposure to stress-inducing stimuli—traffic congestion, high noise levels, monotonous visual landscapes, air pollution, and limited green spaces—consistently activates the body’s stress system. The dominance of gray concrete, asphalt, and pollution-reduced visibility contributes to sensory deprivation, reducing dopamine and serotonin-generating stimuli. Restricted access to natural light due to smog and dense vertical development disrupts melatonin cycles, sleep quality, and emotional stability. Social interaction is further constrained by limited public spaces, long commuting distances, and insufficient pedestrian-friendly infrastructure, which reduce oxytocin release and contribute to feelings of isolation. Collectively, these factors create an urban ecosystem that suppresses neurohormonal balance and undermines psychological resilience.
Copenhagen, by contrast, demonstrates how intentional urban design can support and strengthen hormonal well-being. The city’s emphasis on natural light—facilitated by low-rise architecture, wide streets, and reflective surfaces—enhances circadian regulation and boosts serotonin levels. Vibrant colors in buildings and public spaces stimulate positive emotional responses. The extensive cycling network and pedestrian infrastructure promote daily physical activity, increasing endorphins and dopamine. Green spaces are abundant, evenly distributed, and easily accessible, fostering relaxation, reducing cortisol, and supporting social engagement. Noise pollution is significantly lower than in car-dominated cities, thanks to reduced reliance on cars and effective environmental policies. Social interaction is facilitated by inviting public spaces, waterfront promenades, and event-friendly plazas, all of which enhance oxytocin and contribute to emotional well-being. Copenhagen thus represents an urban model aligned with human biological needs.
The comparative analysis yields several insights. First, environmental quality plays a critical role in moderating the interaction between genetic susceptibility and emotional experience. Individuals predisposed to anxiety or depression may experience intensified symptoms in stress-inducing environments such as Tehran, whereas in Copenhagen’s low-stress context, environmental conditions may help neutralize genetic vulnerabilities. Second, the design of urban infrastructure directly affects physical activity, sleep, stress levels, and social connection—each of which is linked to hormonal regulation. Third, sensory richness—achieved through thoughtful use of color, sound, light, and natural elements—contributes significantly to emotional vitality and cognitive engagement.
Building upon these insights, the study proposes several design recommendations: maximizing exposure to natural light in residential, educational, and work environments; employing color palettes that evoke positive emotional responses; integrating noise mitigation strategies and natural soundscapes; expanding green and blue infrastructure; enhancing walkability and cycling networks to encourage endorphin-generating physical activity; and designing public spaces that foster social interaction and cultural engagement. These interventions not only promote individual mental health but also strengthen community cohesion, reduce burdens on the healthcare system, and enhance long-term urban resilience.
In conclusion, the research demonstrates that urban environments function as neurobiological regulators that shape hormonal balance and psychological outcomes. The sensory and social qualities of a city—its light, sound, color, movement, and social opportunities—directly influence the secretion of serotonin, dopamine, oxytocin, and endorphins. The contrast between Tehran and Copenhagen illustrates that pedestrian-centered, sensory-rich, socially cohesive environments promote optimal hormonal conditions for happiness, while car-centered, high-stress cities may disrupt these processes. Ultimately, the study underscores the importance of integrating biological and psychological knowledge into urban design practice. Cities that align with human neurohormonal needs have the potential to become catalysts of happiness, resilience, and long-term well-being, transforming urban living into a supportive, health-enhancing experience rather than a source of chronic stress.
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