Revising and extending the model of human circadian phototransduction
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Authors
Nagare, Rohan
Issue Date
2019-12
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Architectural sciences
Alternative Title
Abstract
Given the advent of non-conventional white light sources devoid of specific short-wavelength radiation (such as the “cyan-gap”), and recent electrophysiological evidence suggesting greater neural complexity of phototransduction pathways in retina, a primary objective of this thesis was to provide further resolution with regard to the spectral sensitivity framework proposed by Rea and colleagues. Another objective was to add a dynamic exposure duration factor to the CS model, as the current model only accounts for a fixed exposure duration of 1-h, and there exists strong evidence suggesting that exposure duration affects the circadian efficacy of the photic stimulus in non-linear manner. The model is also largely static with regard to accounting for physiological traits of the population, hence, the thesis also aimed to describe age and macular pigment optical density (MPOD) induced changes to the spectral and absolute sensitivities of the human circadian system. Overall, six nighttime studies with salivary melatonin suppression as the dependent variable were conducted between February 2017 and May 2019, to improve and extend the original model. Collectively, participants from distinct age-groups and varying MPOD values (0.02 – 0.81) were exposed to a specialty white light source (“cyan-gap” with reduce radiant power between 475 and 495 nm) and several other conventional white light sources (rated correlated color temperatures or CCTs – 2700 K, 3300 K, 4000 K, 4300 K, 5000 K and 6500 K), at varying light levels (40–1000 lux ) and exposure durations (0.5–3.0 h). In the wake of ambiguity concerning the ability of the circadian system to integrate photic stimuli spatially, a study was also conducted to examine how two different lighting distribution patterns for a narrow-band light LED source (451 nm) could affect nocturnal melatonin suppression.
Description
December 2019
School of Architecture
School of Architecture
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY