How Light Reshapes the Mind. An Active Inference Framework for the Cognitive and Emotional Effects of Indoor Lighting

Indoor lighting affects cognition, affect, and behavioural regulation, but these effects are often treated as isolated findings rather than as parts of a unified process. This paper proposes an active inference account of shared indoor lighting in multi-user environments such as offices, classrooms, and libraries. It argues that lighting shapes behaviour through three distinct channels: illuminance modulates perceptual precision, correlated colour temperature modulates arousal relative to circadian optimum, and spectral composition biases behavioural disposition toward engagement or rest. The paper formalises this hypothesis through a proof-of-concept POMDP model of agents performing sustained reading over five hours, using both reading performance and eye-tracking observations. The model generates six falsifiable predictions, all confirmed across 20 Monte Carlo simulations.