Daylight is widely valued in educational buildings for visual comfort, wellbeing, and energy efficiency, yet poorly controlled daylight can introduce discomfort glare, uneven illumination, and visual fatigue that disrupt learning activities. This study investigates how daylight conditions influence students’ psychological responses and study behavior in the main university library at Eastern Mediterranean University (EMU), Famagusta, North Cyprus (Aram and Alibaba 2018). A mixed-methods case-study design combined systematic on-site observations of coded study areas and a two-part questionnaire administered during daylight hours (10 a.m.–5 p.m.) with simulation-based estimates of solar radiation and solar heat gain from Autodesk Ecotect Analysis. Results show that many users valued daylight and associated it with a pleasant study atmosphere, but these benefits depended on balanced distribution and effective glare control. Roof apertures and tall vertical windows produced localized high-contrast conditions and reflections on work surfaces and electronic devices, leading to recurring discomfort in several areas. Morning conditions with predominantly indirect daylight were more often linked to higher reported alertness and concentration, whereas early-afternoon and late-day conditions with direct sun patches or low ambient light were associated with fatigue and reduced focus; users responded by relocating seats, using blinds, or avoiding affected locations. Seasonal solar position altered modeled radiation and heat gain, yet behavioral adaptation aligned more consistently with perceived visual conditions than with heat gain alone. The study highlights the need for integrated daylight management—coordinated layout planning, reduced specular interior finishes, and adaptable shading and glazing—to improve visual comfort and support sustained study performance in contemporary library environments.