What Is Human-Centric Lighting? A Quick Guide to HCL
Posted March 3, 2026 by Natalie
We spend 90% of our time indoors yet our bodies are still wired for natural daylight. A lack of sunlight and its visual – as well as non-visual – benefits can be detrimental to our health. So what can we do? Step forward Human-Centric Lighting (HCL). We’re receiving more and more enquiries about this emerging concept, so we’ve created this simple overview to explain how HCL works, why it matters and where it’s used.
Human-Centric Lighting: A Definition
Electric lighting was originally designed for indoor spaces, not for the people who use them. In contrast Human-Centric Lighting means lighting that:
- Is human-focused
- Blends dynamic electric light with natural daylight
- Supports mood, sleep, energy & productivity
HCL (also known as circadian, tunable white or biodynamic lighting) is not a product – it’s a combination of insightful design and smart technology. Although it can’t replace daylight, increasing research shows that it can replicate some of its positive effects. Hooray!
How Does Human-Centric Lighting Work?
Daylight is the most important factor in regulating our circadian rhythm - our internal 24-hour biological clock. This in turn influences physiological processes such as healthy production of melatonin (sleep hormone) and cortisol (alertness hormone). The artificial light we use indoors is static; it doesn’t change in the same way that natural light changes in response to:
- The day-night cycle
- Seasonal variation
- Weather patterns
- Global latitude
Artificial light disrupts our natural sleep-wake cycle, whereas HCL works in harmony with our biological rhythms. Humans need dynamic light that mimics the light we see in nature – from dappled sunlight to glowing fire light – in order to optimally regulate our hormones and promote our general wellbeing.
The Benefits of Human-Centric Lighting
Scientific studies are showing that HCL:
- Improves natural sleep cycles which:
- Promotes patient recovery in hospitals
- Improves traveller jet lag in hotels
- Encourages better mood regulation in those affected by:
- Seasonal Affective Disorder (SAD)
- Dementia
- Mental health issues
- Promotes health and wellbeing by providing:
- Better visual comfort
- Less eye strain & headaches
- Reduced cases of myopia (short-sightedness) in children
- Increases productivity and focus by:
- Enhancing alertness in offices & schools
- Supporting shift workers during irregular working hours
How to Create a Human-Centric Lighting System
Clever design, including:
- All the fundamentals of great lighting design e.g. visual comfort, glare control & layers of light
- Considering each individual environment, who uses it & how it is used
- Daylight integration with artificial light
- Lighting vertical, as well as horizontal, surfaces
- Measuring how much light reaches the eye (not just the desk surface)
Smart products, such as:
- Daylight & occupancy sensors
- Tunable LEDs
- Automated intelligent controls
Smart technology allows for a dynamic lighting system by adjusting:
- Light colour, e.g.:
- Cool white light (5000–7000K) boosts alertness
- Warm white light (2700–3500K) supports relaxation & sleep
- Light intensity:
- Both light intensity and duration of exposure affect biological response
- E.g., research recommends our eyes are exposed to 250 melanopic lux for 30 mins in the morning to regulate our sleep cycles effectively
Research, technology and best practices are still evolving, so it’s essential for HCL systems to be flexible in order to adapt to any changes necessary.
HCL – The Future of Lighting Looks Healthy
Human-Centric Lighting represents a move towards healthier, human-focused architectural design (it’s now included in the WELL Building Standard criteria). The mainstream demand for blue light glasses and infrared light therapy demonstrates our awareness of the whole spectrum of benefits that light has to offer - beyond the visible. And when lighting supports your biology, life just feels that little bit brighter.
