Architecture is considered a crossing field between arts and sciences that is supported by multiple, various and complex issues. Considering that architecture is a man's creation for men, this research explores human factors in architecture. It specifically focuses on the relationships between users and natural lights (both sunlight and daylight) within houses and public buildings designed during the 20th century modernist era by renowned architects. The investigative approach relies mainly on a literature review as well as in site observations and some interviews for the case studies in France. Six contemporary architects' work composed the study corpus. The results highlight first that i) users did not perceive natural light as architects intended it, ii) users' sensations could not replace the essential requirements contributing to satisfaction with a comfortable daylit space, and iii) after the disappearance of the sensation first effect, dissatisfaction occurred and often generated transformations disfiguring the striking effects previously designed by the architects.