研究目的
To evaluate the relative photoreceptors' involvement by modelling the relationships between alpha-opic illuminances and melatonin suppression, and to test the goodness of the model with data from our laboratory.
研究成果
Melatonin suppression is predominantly driven by melanopsin, with high sensitivity to low light levels (initiation at ~1.5 melanopic lux and saturation at ~305 melanopic lux). The model predicts suppression well across datasets, emphasizing the non-visual impacts of light in experimental settings and the need for caution in extrapolating to real-life conditions.
研究不足
The model is derived from a single dataset (Brainard et al.) and validated on another (Najjar et al.), both under highly controlled conditions with monochromatic lights, dilated pupils, and specific circadian phases. It may not apply to polychromatic lights, real-life conditions, different exposure durations, or other circadian phases. Factors like prior light history, age, gender, and medical conditions could affect thresholds.
1：Experimental Design and Method Selection:
The study involved re-analyzing an extensive dataset from Brainard et al. (2001, 2008) and using a four-parameter logistic model to fit dose-response curves for melatonin suppression as a function of alpha-opic illuminances. Nonlinear least squares fitting procedures in R v.
2：1 were used. Sample Selection and Data Sources:
Data from Brainard et al. (2001, 2008) included subjects exposed to monochromatic lights of eight wavelengths (420-600 nm) at various intensities, with participants aged 18-30 years. Data from Najjar et al. (2014) included young participants (n=5, 24-27 years old) exposed to monochromatic lights of nine wavelengths (420-620 nm) at equal photon density.
3：List of Experimental Equipment and Materials:
Pupil dilation with antimuscarinic eye drops, monochromatic light sources with specified wavelengths and FWHM, plasma melatonin measurements, and software like WebPlotDigitizer V
4：1 for data extraction. Experimental Procedures and Operational Workflow:
For Brainard et al. data, subjects were dark-adapted, pupils dilated, exposed to light from 0200-0330 h, and melatonin suppression calculated. For Najjar et al. data, similar procedures with light exposure from 0030-0130 h. Alpha-opic metrics were calculated for each light exposure.
5：Data Analysis Methods:
Melatonin suppression was plotted against alpha-opic illuminances, and dose-response curves were fitted using a four-parameter logistic model. Correlation coefficients (R2) were used to assess goodness of fit.
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