Excess lighting linked to bad moods

Posted by Rob Gemmell on Sep 2, 2014 7:27:00 AM


Specification of low profile lighting is about more than seamless integration into a building's architecture and energy efficiency, as new research shows cutting down on direct lighting is also linked to making occupants less grumpy.


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King County Library System, Snoqualmie Branch, Snoqualmie, WA | Architecture: Miller Hull Partnership | Lighting: Vode System stack mounted WingRail | Image: Yoram Bernet

Research from Johns Hopkins University showed that too much light can be just as detrimental to our happy feelings as too little light. The study found that irregular bright light exposure increases levels of corticosterone, a stress hormone. Chronic exposure to bright light had negative effects on mood-related behaviors as well as cognitive functions, even though circadian rhythm and sleep-wake cycles were unaffected.

The study was conducted on mice, which have special vision cells similar to those found in humans. These intrinsically photosensitive retinal ganglion cells, or ipRGCs, are activated by bright light and cause changes in the brain in relation to memory, learning and mood.


Implications for commercial lighting design

The researchers introduced the mice to 3.5 hours of light followed by 3.5 hours of darkness. This alternation led to a drop in pleasure-seeking activities and depression-like symptoms. Additionally, the mice had problems learning and remembering tasks.

At night, less exposure to intense light can alleviate these symptoms. In settings that operate in the evening hours, the use of dimming controls and indirect lighting can be beneficial. In applications where fixtures need to be directed toward occupants or tasks, dimmers can lower the light's intensity while providing necessary illumination. For ambient lighting applications, linear perimeter and cove fixtures can provide an indirect, ubiquitous glow.


A minimalist lighting approach

Using only the necessary amount of light, or designing for easy dimming can prevent unwanted activation of ipRGCs, thereby easing depressive moods and making occupants happier. This approach can be especially useful for environments with late-shift workers or late-night entertainment venues such as bars and movie theaters.

Topics: lighting quality, mood, dimming, lighting and health