When Darkness Falls: What Light Does to Us
PhD candidate Richard Jedon shows how alertness, arousal, and anxiety influence safety perception and lighting demand. HTI research helps cities balance energy, ecology, and pedestrian safety.
PhD researcher Richard Jedon explored how people behave in the dark and what that means for public lighting. Within Human Technology Interaction (HTI), he shows that not just brightness, but internal processes like alertness, arousal, and anxiety determine how much light pedestrians want and how safe they feel.
Why Now
Cities depend on artificial light for life after sunset, yet concerns about light pollution, energy use, and costs grow. Jedon demonstrates that current standards lack solid empirical foundations and that safety must be understood through internal processes.
The Triad
Jedon introduces a framework of alertness, arousal, and anxiety. This triad explains earlier findings and guides new methods for measuring perceived safety, adding depth to century-old research on lighting and alertness.
Findings
Field studies showed non-uniform lighting increased alertness and that arousal strongly correlated with perceived safety. Laboraty experiments confirmed these links and revealed that arousal itself -independent of lighting - can shift safety perception. Further tests showed tense arousal and anxiety reduce tolerance for darkness, increasing demand for light. Visual appearance of lighting patterns proved as influential as brightness.
Relevance
For cities and designers, good lighting isn’t about one standard number. It requires context-specific solutions that respond to human needs while saving energy and protecting nature. Jedon’s work offers a foundation for revising norms toward human-centered, efficient designs.
Richard Jedon defended his thesis on January 22. His research was awarded cum laude. Thesis title: . Supervisors: Yvonne de Kort and Antal Haans.
PhD awards with the honor of ‘cum laude’ are relatively rare, and recognized among the top 5% in the research area. To be eligible the PhD work must be of exceptional quality, and must be performed with an exceptional level of autonomy.