Light plays a critical role in our ability to see via day and night vision. But just as important, nonvisual receptors in the eye regulate our internal body clock, sleep patterns, and overall wellbeing.
Traditional lighting design primarily focuses on visual comfort, ambiance, and task illumination. However, recent scientific studies and technological advancements have introduced the importance of melanopic lighting, which specifically targets the nonvisual effects of light on human health.
There’s science behind melanopic lighting.
The day and night vision photocells in our eyes have a direct pathway to the visual cortex, enabling us to see the world. But our eyes also contain special light-sensitive cells called intrinsically photosensitive retinal ganglion cells (ipRGCs) which communicate with the suprachiasmatic nucleus – a separate area in the brain imperative to health and wellbeing.
These cells contain a photopigment called melanopsin, which is most sensitive to the visually blue-green wavelengths. When stimulated by these wavelengths of light, melanopsin triggers various nonvisual responses in the body, including:
- Regulation of circadian rhythm: The circadian rhythm is the internal 24-hour cycle that governs our sleep/wake patterns, hormone production, and other physiological processes. Appropriate melanopic light exposure helps synchronize the circadian rhythm with the external light/dark cycle.
- Alertness and cognitive function: Studies suggest that exposure to high levels of melanopic light during the daytime can improve alertness, focus, and cognitive performance.
- Sleep quality: Increasing melatonin production in the evening through reduced melanopic light exposure can promote better sleep quality.
Designers have new metrics.
Lighting design now has another component for consideration – the electric light and how its melanopic light variations aid in human wellness.
To quantify the non-visual effects of light, two new metrics have been standardized:
- Melanopic equivalent daylight illuminance (melanopic EDI): This metric measures the stimulating effect of light on melanopsin-based photoreception. A higher melanopic EDI results in a stronger potential to influence nonvisual responses, including concentration, alertness, and energy levels.
- Melanopic daylight efficacy ratio (melanopic DER): This metric compares the melanopic effectiveness of an electrical light source to standard daylight (D65). A light source with a higher melanopic DER can achieve the same melanopic effect with less energy compared to a source with a lower melanopic DER.
What are the benefits of melanopic lighting for facility occupants?
Implementing melanopic lighting strategies in facilities offers several potential benefits, including:
- Improved employee alertness and productivity: By supporting a healthy circadian rhythm and promoting daytime alertness, melanopic lighting can enhance worker focus, performance, and productivity.
- Enhanced sleep quality: By minimizing evening exposure to melanopic light, facilities can contribute to better sleep quality for employees, leading to increased overall wellbeing.
- Increased occupant satisfaction: A well-designed lighting system that considers both visual and nonvisual melanopic lighting effects throughout the day, can create a more comfortable and stimulating working environment.
How to design healthier spaces with melanopic lighting in mind.
While research on melanopic lighting is ongoing, some initial case studies and recommendations can guide facility lighting design:
- Maximize melanopic EDI at peak hours during the daytime: While prioritizing visual comfort and safety, aim to provide sufficient melanopic light exposure during work hours to support human circadian rhythm and attentiveness.
- Consider dynamic lighting solutions: Implement lighting systems that adjust color temperature and intensity throughout the day, but more important, contain the right melanopic characteristics which mimic natural daylight melanopic patterns.
- Minimize melanopic light exposure in the evening: For areas used in the evening, consider lighting with lower melanopic content to promote relaxation and sleep preparation.
Recent technology advancements in LED lighting systems allow for more indoor, deliberate control of the melanopic stimuli. By incorporating melanopic lighting principles, we can create healthier and more productive indoor environments. As research progresses, our understanding of the impact of melanopic lighting on human health will continue to evolve, informing further advancements in lighting design for improved well-being.
Solutions that appropriately address the biological impact of light throughout the day by enhancing the melanopic spectrum will undoubtedly change the dialogue around indoor lighting design and control.
Designing interiors to reflect outdoor color and spectrum characteristics can support healthy circadian rhythms which regulate our sleep/wake cycle, daytime engagement, and mood—all without distorting traditional lighting design metrics, such as visual color perception, ambiance, and task illumination.