Applying Melanopic Lux to Measure Biological Light Effects on Melatonin Suppression and Subjective Sleepiness

Author(s): Claudia Nowozin , Amely Wahnschaffe, Andrea Rodenbeck , Jan de Zeeuw, Sven Hädel , Ruslan Kozakov , Heinz Schöpp, Mirjam Münch*, Dieter Kunz*.

Journal Name: Current Alzheimer Research

Volume 14 , Issue 10 , 2017

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Objective: At the beginning of this century, a novel photopigment, melanopsin, was discovered in a sub-class of retinal ganglion cells and its action spectrum was described. Shortly after, it became evident that melanopsin is a major contributor to non-visual eye-mediated effects of light on e.g. the circadian, neuroendocrine and neurobehavioral systems. First applied studies pointed out that these non-visual effects of light are relevant for wellbeing, performance and general health. A standardized measurement metric for these nonvisual effects does not exist, but would ease application. Such a metric termed as ‘melanopic lux’ has been recently introduced and was shown to be superior to describe non-visual effects in animal studies compared to standard metrics.

Methods: We aimed at showing some validity of melanopic lux in humans using a seminaturalistic setting. Therefore, we analyzed the impact of different lighting conditions on melatonin suppression and subjective sleepiness by calculating effective illuminance based on single photopigment sensitivities. We retrospectively analyzed data from our laboratory, where young participants were exposed to a total of 19 different polychromatic lighting conditions, for 30 minutes in the evening, one hour prior to habitual bedtime. Saliva samples for melatonin concentration measures and subjective sleepiness were regularly assessed. The photopic illuminance of all lighting conditions ranged from 3 to 604 lx. Stepwise for- and backward regression analyses showed that melanopic lux was the best predictor for changes in melatonin concentrations (but not subjective sleepiness); R²=0.16 (p<0.05). In addition, we found a significant dose-response relationship between melanopic lux and changes in melatonin concentrations for 18 different lighting conditions (adjusted R²=0.52; p=0.004), similarly to what was previously reported for photopic lux.

Results: Our results indicate some new relevance for the application of melanopic lux as an additional metric to predict non-visual light effects of electrical light sources for nursing homes, work places, and homes.

Keywords: Melatonin suppression, short-term light exposure, light perception, subjective sleepiness, ganglion cells, Alzheimer’s disease.

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Article Details

Year: 2017
Page: [1042 - 1052]
Pages: 11
DOI: 10.2174/1567205014666170523094526
Price: $58

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