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.
Harvard Medical School research (2023) found that interiors adopting a circadian lighting protocol improved occupant sleep quality by roughly 23%. 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 (Harvard Medical School measured about 23% improvement) and supports cardiovascular and cognitive health.
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