Summary
The GENEActiv Original wrist-worn device shows strong linear correlation with photopic illuminance but consistently under-reports light levels, particularly below 100 lux — a range critically important for circadian system sensitivity. Researchers and lighting practitioners using this device should supplement measurements with light source type data, as accuracy varies substantially by spectral composition (under-reporting green, over-reporting red) and is compromised by infrared exposure.
Key Findings
- The GENEActiv Original consistently under-reported photopic illuminance, with the greatest inaccuracy below 100 lux — the range of highest circadian sensitivity in humans.
- Accuracy below 100 lux was source-dependent: lower accuracy and higher variability were observed under fluorescent lighting compared to other sources.
- The device under-reported photopic illuminance for green light sources and over-reported for red light sources, indicating spectral bias.
- Infrared light exposure meaningfully impacted photopic illuminance readings, introducing additional measurement error.
- The device was deemed suitable for distinguishing indoor vs. outdoor lighting patterns within individuals, but not for precise low-light circadian exposure quantification.
Categories
Sleep & Circadian Health: Evaluates a wrist-worn light sensor used in circadian and sleep research for accuracy across ecologically relevant lighting conditions.
The Science of Light: Addresses spectral sensitivity, photopic illuminance measurement accuracy, and implications for circadian light exposure assessment using wearable devices.
Author(s)
JE Stone, EM McGlashan, ER Facer-Childs, SW Cain
Publication Year
2020
Number of Citations
18
Related Publications
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The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice