Centre for Biological Timing, Faculty of Medicine, Biology and Health, University of Manchester, Manchester, UK.
J Pineal Res. 2020 Aug;69(1):e12655. doi: 10.1111/jpi.12655. Epub 2020 Apr 19.
Ocular light drives a range of nonvisual responses in humans including suppression of melatonin secretion and circadian phase resetting. These responses are driven by intrinsically photosensitive retinal ganglion cells (ipRGCs) which combine intrinsic, melanopsin-based, phototransduction with extrinsic rod/cone-mediated signals. As a result of this arrangement, it has remained unclear how best to quantify light to predict its nonvisual effects. To address this, we analysed data from nineteen different laboratory studies that measured melatonin suppression, circadian phase resetting and/or alerting responses in humans to a wide array of stimulus types, intensities and durations with or without pupil dilation. Using newly established SI-compliant metrics to quantify ipRGC-influenced responses to light, we show that melanopic illuminance consistently provides the best available predictor for responses of the human circadian system. In almost all cases, melanopic illuminance is able to fully account for differences in sensitivity to stimuli of varying spectral composition, acting to drive responses that track variations in illumination characteristic of those encountered over civil twilight (~1-1000 lux melanopic equivalent daylight illuminance). Collectively, our data demonstrate widespread utility of melanopic illuminance as a metric for predicting the circadian impact of environmental illumination. These data therefore provide strong support for the use of melanopic illuminance as the basis for guidelines that seek to regulate light exposure to benefit human health and to inform future lighting design.
光刺激眼部能引发人类一系列非视觉反应，包括褪黑素分泌抑制和昼夜节律相位重置。这些反应由内在感光视网膜神经节细胞(ipRGCs)驱动，它们将内在的、基于视黑质的光转导与外在的视杆/视锥介导的信号相结合。由于这种结构，目前仍不清楚如何最好地量化光刺激以预测其非视觉效应。为了解决这个问题，我们分析了来自 19 项不同实验室研究的数据，这些研究测量了人类对各种刺激类型、强度和持续时间的褪黑素抑制、昼夜节律相位重置和/或觉醒反应，包括瞳孔扩张和不扩张的情况。使用新建立的符合 SI 标准的指标来量化光对 ipRGC 影响的反应，我们表明，视黑素辐照度始终是预测人类昼夜节律系统反应的最佳可用指标。在几乎所有情况下，视黑素辐照度都能够完全解释对具有不同光谱组成的刺激的敏感性差异，从而驱动与民用曙光期间（~1-1000lux 视黑素等效日光辐照度）遇到的光照特征变化相匹配的反应。总的来说，我们的数据表明视黑素辐照度作为预测环境光照对昼夜节律影响的指标具有广泛的适用性。因此，这些数据为使用视黑素辐照度作为规范光暴露的基础提供了强有力的支持，以促进人类健康，并为未来的照明设计提供信息。
