Research from Shanghai’s Fu-tan University investigating the effect of indoor LED lighting has shown that sufficient light with high biological efficiency during the day leads to higher daytime whiteness and night-time sleep quality.

About study

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Title:	Influence of the spectrum of all-day LED lighting on human daytime and night-time performance
Author:	Nuoyi Li, Sicong Zhou, Wenqing Miao, Congshan Dai, Ali Hassan Shah, Yandan Lin School of Information Science and Engineering, Fudan University, Shanghai, China
Date:	15. February 2023
Source:	https://ieeexplore.ieee.org/document/10071053
PDF:	Influence of the spectrum of all-day LED lighting on human daytime and nighttime performance.PDF

Brief summary

A Chinese study confirmed the impact of LED lighting on health, sleep, and performance. The research focused on the effects of the spectral composition of LED lighting on human performance during the day and sleep quality at night. Six types of LED sources were selected for the experiment: standard LEDs and LEDs mimicking full-spectrum sunlight during the day, with CCT values of 2700 K, 4000 K, and 5000 K. The results showed that daytime exposure to interior lighting with a stronger non-visual stimulus (higher melanopic EDI) led to increased daytime alertness and better quality of nighttime sleep. Conversely, a lack of daytime light stimuli contributed to worsened nighttime sleep quality.

Daily exposure to light with stronger non-visual stimuli led to higher daytime alertness and improved sleep quality

The study found that daily exposure to light with stronger non-visual cues, as measured by the melanopic equivalent of daylight illumination (mEDI), significantly improved daytime alertness and sleep quality. The mEDI index assesses the biological effects of light on non-visual functions such as the regulation of circadian rhythms. Research has shown that people who were exposed to higher levels of mEDI during the day showed better alertness, concentration and better quality sleep, probably due to more consistent regulation of the biological clock. This result underlines the importance of optimal daylight exposure with high melanopic efficacy for human health, performance and well-being.

Low daytime mEDI levels in lighting led to poor sleep quality

In the study, CS and melanopic EDI were shown to be able to predict the trend of changes in daytime alertness and night-time sleep quality.
Specifically, the study revealed that low levels of daytime non-visual stimuli led to poor sleep quality, while high levels of non-visual stimulation during the day led to high sleep quality at night.