The accuracy of artificial and natural light measurements by actigraphs
Article
Article Title | The accuracy of artificial and natural light measurements by actigraphs |
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ERA Journal ID | 16495 |
Article Category | Article |
Authors | Joyce, Daniel, Zele, Andrew J., Feigl, Beatrix and Adhikari, Prakash |
Journal Title | Journal of Sleep Research |
Journal Citation | 29 (5), pp. 1-7 |
Article Number | e12963 |
Number of Pages | 7 |
Year | Oct 2020 |
Publisher | John Wiley & Sons |
Place of Publication | United Kingdom |
ISSN | 0962-1105 |
1365-2869 | |
Digital Object Identifier (DOI) | https://doi.org/10.1111/jsr.12963 |
Web Address (URL) | https://onlinelibrary.wiley.com/doi/10.1111/jsr.12963 |
Abstract | Actigraphs are the reference standard for measuring light exposure in human non-laboratory experiments due to their portability and long battery lives. However, actigraphs typically have a limited illuminance operating range not representative of real-world conditions, and for many actigraphs, the accuracy of their light measurement has not been verified independently. We assessed the illuminances recorded by Activinsights GENEActiv Original and Philips Actiwatch 2 actigraphs in comparison to a calibrated, laboratory-standard photometer, under both artificial light-emitting diode (LED) and natural sunlight illuminations that might be encountered by a person under real-world conditions. We show that in response to ~20,000 lux white LED light, the GENEActiv and Actiwatch 2 underestimate illuminance by recording 50% and 25% of the true value, respectively. Under ~30,000 lux sunlight, the GENEActiv readily saturates whereas the Actiwatch 2 reports ~46% of the true illuminance. These underestimations are highly linear and we provide correction factors to estimate the illuminance levels of the ambient environment measured by the actigraphs. We also evaluate the application of neutral density filters for extending the operating range of both devices in natural sunlight illuminations (as high as 30,000 lux during our measurements) and demonstrate that this may be a viable approach for increasing the operating range of the Actiwatch 2 but not the GENEActiv. We conclude that both actigraphs provide good performance in monitoring the temporal patterning of light, whereas the absolute illuminance values require correction to accurately evaluate the effects of light intensity on human health and behaviours. |
Keywords | illuminance; LED; light exposure; photometer; sunlight |
ANZSRC Field of Research 2020 | 400909. Photonic and electro-optical devices, sensors and systems (excl. communications) |
321204. Vision science | |
520406. Sensory processes, perception and performance | |
Public Notes | File reproduced in accordance with the copyright policy of the publisher/author. |
Byline Affiliations | Queensland University of Technology |
Queensland Eye Institute, Australia |
https://research.usq.edu.au/item/w3v16/the-accuracy-of-artificial-and-natural-light-measurements-by-actigraphs
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