Longevity by Design · Pillar · CLCI
Circadian Light Compliance Index
The Circadian Light Compliance Index is the first pillar of the Longevity by Design methodology. It scores how closely a space’s lighting follows the human circadian rhythm across a full day: cool, blue-rich light during daylight hours (4000–5000 Kelvin) signals wakefulness, while warm amber light in the evening (2200–2700 K) lets the melatonin curve rise naturally.
In a randomized clinical trial, circadian-aligned lighting improved sleep-quality scores by roughly a third (Figueiro et al., Journal of Clinical Sleep Medicine, 2020). Poor sleep is independently linked to cardiovascular disease and cognitive decline, which is why light timing is treated as a measurable health intervention rather than a decorative choice. In practice the CLCI is delivered through tunable-white luminaires on an automated daily schedule, glare-controlled task lighting, and layouts that maximise morning daylight.
Frequently asked
What is the Circadian Light Compliance Index?
It is the lighting pillar of the Longevity by Design methodology — a score for how well a space’s light spectrum and timing align with the human circadian rhythm (4000–5000 K by day, 2200–2700 K in the evening).
Why does light colour temperature matter for health?
Cool light by day and warm light at night keep the melatonin curve aligned, which improves sleep quality (Figueiro et al., Journal of Clinical Sleep Medicine, 2020: sleep-quality scores improved by roughly a third in a randomized trial) and supports cardiovascular and cognitive health.