Lighting Impacts on Circadian Rhythms

Green Building

Lighting Impacts on Circadian Rhythms

Originally published on July 11, 2016 by BNP Media through the Architectural Roofing & Waterproofing Blog.
With the emergence of human health concerns, wellness, and biophilia as priorities in the building design and construction industry, the lighting profession is shifting its focus toward circadian lighting design.

Light is one of the main drivers of circadian rhythms – that is, our internal clock that keeps the body’s hormones and bodily processes on a diurnal cycle, even in continuous darkness. When the human body receives light – any kind of light – the brain is stimulated and regulates physiological rhythms throughout the body’s tissues and organs, impacting hormone levels and the sleep-wake cycle.


Circadian Rhythms

Circadian rhythms are kept on a regular cycle by various cues from the environment, including light. One of the ways in which the human body responds to light is facilitated by intrinsically photosensitive ganglion cells (ipRGCs). Essentially, ipRGCs are the are eyes’ non-image-forming photoreceptors. They relay environmental light levels to the suprachiasmatic nucleus in the brain through the retinohypothalamic tract – this is the main clock that acts as an oscillator to synchronize clocks in peripheral tissues and organs. High frequency light will promote bodily alertness, while a lack of light will cue the body to reduce energy expenditures and prepare for rest.

Moreover, ipRGCs are especially sensitive to blue light. Skylight is going to prompt the brain to become more awake and alert. This is why staring at a tablet screen before sleeping might not be such a good idea for those with sleeping difficulties.

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