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

Laura Bellia,Francesca Fragliasso

doi:10.3390/ijerph18031002

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.

Highlights

IntroductionIt is commonly accepted that light has multiple effects on people, not limited to visual perception, but consisting in human responses of different types: circadian responses (referring to the regulation of the biological processes based on a 24 h cycle), neuroendocrine responses (referring to hormone production) and neurobehavioral responses (referring to the relationship between the action of the nervous system and human behavior) [1].Practically, this means that light influences aspects like body temperature regulation [2,3], heart rate modulation [4], variation in alertness state [5], mood [6], work performance [7,8]and, melatonin suppression and, the sleep–wake cycle [9,10].a proper exposure to light is fundamental to synchronize circadian rhythms and guarantee sleep quality
The paper has underlined the fundamental role of architectural design in defining the quantity and the quality of light received by people during the day
It has highlighted how complex it is to evaluate the mutual interactions between light and architecture to define their effect on circadian systems

Summary

Introduction

It is commonly accepted that light has multiple effects on people, not limited to visual perception, but consisting in human responses of different types: circadian responses (referring to the regulation of the biological processes based on a 24 h cycle), neuroendocrine responses (referring to hormone production) and neurobehavioral responses (referring to the relationship between the action of the nervous system and human behavior) [1].Practically, this means that light influences aspects like body temperature regulation [2,3], heart rate modulation [4], variation in alertness state [5], mood [6], work performance [7,8]and, melatonin suppression and, the sleep–wake cycle [9,10].a proper exposure to light is fundamental to synchronize circadian rhythms and guarantee sleep quality. It is commonly accepted that light has multiple effects on people, not limited to visual perception, but consisting in human responses of different types: circadian responses (referring to the regulation of the biological processes based on a 24 h cycle), neuroendocrine responses (referring to hormone production) and neurobehavioral responses (referring to the relationship between the action of the nervous system and human behavior) [1]. This means that light influences aspects like body temperature regulation [2,3], heart rate modulation [4], variation in alertness state [5], mood [6], work performance [7,8]. The photoreceptors mainly responsible for non-visual effects of light, intrinsically photosensitive retinal ganglion cells (ipRGCs), are more sensitive to short wavelengths, being characterized by a spectral sensitivity curve peaking at 490 nm [11]

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