Longevity by Design · Pillar · CLCI
Circadian Light Compliance Index
Published: June 2026 · Updated: August 2026
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 of 4000–5000 Kelvin supports wakefulness during daylight hours. Warm amber light of 2200–2700 K in the evening lets the melatonin curve rise naturally.
The evidence is clinical. Circadian-aligned lighting improved sleep-quality scores by roughly a third in a randomized trial. The study is Figueiro et al., Journal of Clinical Sleep Medicine, 2020. Poor sleep is independently linked to cardiovascular disease and cognitive decline. Light timing is therefore treated as a measurable health intervention, not a decorative choice.
In practice, the CLCI is delivered through tunable-white luminaires on an automated daily schedule. Glare-controlled task lighting protects visual comfort. Layouts are arranged to maximise morning daylight.
Frequently asked
What is the Circadian Light Compliance Index?
It is the lighting pillar of the Longevity by Design methodology. It scores how well a space’s light spectrum and timing follow the circadian rhythm. The targets are 4000–5000 K by day and 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. A randomized trial improved sleep-quality scores by roughly a third (Figueiro et al., 2020, Journal of Clinical Sleep Medicine). Aligned light also supports cardiovascular and cognitive health.