Definition:
Circadian lighting is the design and implementation of lighting systems that support the human body’s natural biological rhythms — the circadian rhythm. By adjusting light intensity, spectrum, and timing, circadian lighting aims to promote healthy sleep–wake cycles, improve mood, and enhance overall wellbeing.
Why it matters:
Modern life often exposes people to light patterns that disrupt their circadian system, particularly due to artificial lighting at night and insufficient daylight during the day. Poor circadian alignment is linked to sleep disorders, fatigue, reduced alertness, and long-term health risks. Circadian lighting solutions aim to counteract these effects by providing biologically effective light at the right times of day.
How it works:
Circadian lighting typically involves:
- Morning exposure to higher intensity, blue-enriched light to boost alertness
- Evening lighting with reduced blue content to support melatonin production
- Dynamic control systems that adjust spectrum and intensity throughout the day
Measurement & Standards:
Metrics like melanopic lux and melanopic equivalent daylight illuminance (MEDI), defined by CIE S 026, are used to quantify circadian-effective light. Devices such as spectral light dosimeters (e.g., Speccy, SOLACE) measure these parameters for research, compliance, and design validation.
Related terms: