###### Abstract
Research on the effect of environmental colour in educational settings often suffers from insufficient systematic and comprehensive methodologies [11]; this inadequacy also extends to the limited research focused specifically on coloured lighting [12]. For example, [PERSON] et al. [13] state that the effects produced by ambient colour are so variable and erratic that deriving practical applications is a challenging task. In a related context, some researchers have suggested that visual disturbances and colour variations may negatively affect academic performance in educational settings [14]. Conversely, other scholars have made concerted efforts to improve the rigour and systematic nature of their research on environmental influences, including the role of colour, in the context of expansive longitudinal studies [15; 16]. Current circumstances evoke increasing concern when we specifically examine students' cognitive processes, which can be delineated as a broad set of brain activities that transpire independently of socio-affective mechanisms, as identified in the existing literature [17]. While a multitude of research on environmental colour, traditionally perceived as such, such as those aggregated by [PERSON] et al. [1], has established correlations between physical colour and cognitive performance, as shown by the in-depth studies of [PERSON] et al. [18] (colours such as red and blue have different incidences on cognitive tasks such as avoidance, concentration or creativity), [PERSON] et al. [19] (establishing the influence of classroom wall colour on attention), [PERSON] et al. [20] (establishing the goodness of dim classroom colours for students' emotionally positive response) and [PERSON] et al. [21] (students' concentration is affected by classroom wall colour), there is a conspicuous deficiency in specific research on the tangible effects of coloured lighting on cognitive processes. A sparse number of studies, exemplified by the research conducted by [PERSON] et al. [5] that examined the influence of coloured lighting on creativity within an academic environment at a German university, along with previous research conducted in primary education settings [11], have endeavoured to address this fundamental question. Of importance is the foundational work established by our predecessor, the research executed by [PERSON] et al. [12], who conducted a comprehensive exploratory intervention in a primary school context with the aim of revealing the cognitive, academic and emotional consequences derived from the adoption of coloured lighting in classrooms, ultimately reaching substantial conclusions that act as a stimulus for further research. However, when we explore the existing literature on CCT and its respective impacts on cognitive processes, we find that the body of research is notably more extensive and substantial. For example, [PERSON] et al. [22] present a comprehensive review of 18 different studies that collectively investigate the complex interaction between CCT and various cognitive functions, concluding that academic performance, attention rate, work speed, productivity and accuracy depend on CCT, with a high rate (of LED light) in comparison to effect size light being the most appropriate, while [PERSON] et al. [23] analyse how CCT specifically influences attention and memory retention, where higher levels of CCT allow for the improvement of both variables. In addition, [PERSON] et al. [24] examine how CCT, together with ventilation, affects critical cognitive functions such as concentration, logical reasoning and processing speed, with cool values of CCT, together with high ventilation, being the optimal values. Despite some degree of overlap with the aims of our current study, these previous investigations do not focus on our specific variable of interest, which is coloured illumination. A comparable situation arises when we direct our literature review towards the effects of environmental colour specifically on students' affective processes.