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Title: Light sensors for objective light measurement in ambulatory polysomnography
Austin Authors: Schembri, Rachel;Spong, Jo;Peters, Allison;Rochford, Peter D ;Wilksch, Philip;O’Donoghue, Fergal J;Greenwood, Kenneth M;Barnes, Maree ;Kennedy, Gerard A ;Berlowitz, David J 
Affiliation: Institute for Breathing and Sleep
Department of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
College of Science, Health and Engineering, La Trobe Rural Health School, La Trobe University, Bendigo, Victoria, Australia
Melbourne Sleep Disorders Centre, Melbourne, Victoria, Australia
School of Science, RMIT University, Melbourne, Victoria, Australia
James Cook University, Singapore, Singapore
School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
Issue Date: 16-Nov-2017
Date: 2017-11-16
Publication information: PLoS One 2017; 12(11): :e0188124
Abstract: Ambulatory polysomnography (PSG) does not commonly include an objective measure of light to determine the time of lights off (Loff), and thus cannot be used to calculate important indices such as sleep onset latency and sleep efficiency. This study examined the technical specifications and appropriateness of a prototype light sensor (LS) for use in ambulatory Compumedics Somte PSG.Two studies were conducted. The first examined the light measurement characteristics of the LS when used with a portable PSG device, specifically recording trace range, linearity, sensitivity, and stability. This involved the LS being exposed to varying incandescent and fluorescent light levels in a light controlled room. Secondly, the LS was trialled in 24 home and 12 hospital ambulatory PSGs to investigate whether light levels in home and hospital settings were within the recording range of the LS, and to quantify the typical light intensity reduction at the time of Loff. A preliminary exploration of clinical utility was also conducted. Linearity between LS voltage and lux was demonstrated, and the LS trace was stable over 14 hours of recording. The observed maximum voltage output of the LS/PSG device was 250 mV, corresponding to a maximum recording range of 350 lux and 523 lux for incandescent and fluorescent light respectively. At the time of Loff, light levels were within the recording range of the LS, and on average dropped by 72 lux (9–245) in the home and 76 lux (4–348) in the hospital setting. Results suggest that clinical utility was greatest in hospital settings where patients are less mobile. The LS was a simple and effective objective marker of light level in portable PSG, which can be used to identify Loff in ambulatory PSG. This allows measurement of additional sleep indices and support with clinical decisions.
DOI: 10.1371/journal.pone.0188124
ORCID: 0000-0003-2543-8722
Journal: PLoS One
PubMed URL:
Type: Journal Article
Appears in Collections:Journal articles

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