Good Places to Live and Sleep Well: A Literature Review about the Role of Architecture in Determining Non-Visual Effects of Light

Abstract

Light plays a crucial role in affecting the melatonin secretion process, and consequently the sleep–wake cycle. Research has demonstrated that the main characteristics of lighting affecting the so-called circadian rhythms are spectrum, light levels, spatial pattern and temporal pattern (i.e., duration of exposure, timing and previous exposure history). Considering that today people spend most of their time in indoor environments, the light dose they receive strictly depends on the characteristics of the spaces where they live: location and orientation of the building, dimensions of the windows, presence of external obstructions, geometric characteristics of the space, optical properties of walls and furniture. Understanding the interaction mechanism between light and architecture is fundamental to design non-visually comfortable spaces. The goal of the paper is to deepen this complex issue. It is divided into two parts: a brief historical excursus about the relationship between lighting practice and architecture throughout the centuries and a review of the available research works about the topic. The analysis demonstrates that despite the efforts of the research, numerous open questions still remain, and they are mostly due to the lack of a shared and clear method to evaluate the effects of lighting on circadian rhythm regulation.

Analysis of the Impact of Working Environment Factors on Employee’s Health and Wellbeing; Workplace Lighting Design Evaluation and Improvement

“…Responses from our survey indicate that night shift workers were more prone to feelings of visual discomfort, headache, and SAD symptoms. Exposure of the body to artificial lighting at night disrupts the circadian rhythms [3,5,16,29,30]. Blue light plays an important role in this disturbance, as it is contained in natural daylight, but also in light-emitting diodes (lights, monitors, screens).…”

“…On the contrary with higher light intensity the amount of serotonin increases and higher levels of serotonin correlate with better mood, feelings of satisfaction and lower chance at depression and anxiety. Several researchers have investigated the effect of natural light and artificial light on human's circadian rhythm and mood [28][29][30][31][32][33].…”

Evaluation of Visual and Nonvisual Levels of Daylight from Spectral Power Distributions Considering Orientation and Seasonality

“…One of the most widespread is Rea et al who defined the circadian stimulus (CS) and the CL A , parameters directly proportional to the levels of night-time light-induced melatonin suppression [29]. This method is not based on any standard but has been adopted by most researchers to define the circadian effect of light [18]. The highest CS, 0.699, is found in the south and east orientations than in the north and east orientations, especially in the winter months (Figure 7).…”

“…An important issue found for accurate visual and nonvisual daylight implications is the limited information available for this analysis because at least six factors triggering nonvisual light effects have been summarized, including the SPD, the irradiance level, the directionality, the timing, the duration, and the history, which are grouped into luminous and temporal categories [11]. Nevertheless, there have been efforts to develop a clear method to evaluate the effects of lighting on circadian rhythm regulation from different perspectives [17,18].…”

“…This research hypothesizes that daylighting SPDs modify the photopic and melanopic levels inside buildings depending on the orientation, seasonality and characteristics of the skydome [17,18]. The aim of this study is to analyse these real seasonal changes in natural sunlight to evaluate how changes in the SPD affect photometric quantities and calculate the variations in circadian magnitudes based on the CIE standard.…”