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What is Human-Centric Lighting?
Human-Centric Lighting (HCL) refers to a human- and health-centered lighting approach that places the biological, emotional, and visual needs of humans at the center. Unlike conventional lighting, which primarily provides adequate brightness and visual comfort, HCL additionally considers the non-visual effects of light1.
The basic principles of Human-Centric Lighting include:
- Biological effectiveness: Supporting the natural circadian rhythm through adapted light colors and intensities
- Emotional well-being: Promoting positive moods through suitable light atmospheres
- Visual quality: Optimal viewing conditions for various activities
- Dynamic adaptation: Changes in light intensity and color throughout the day
When planning an HCL solution, all these aspects are considered holistically to create lighting that is not only functional but actively contributes to the well-being and health of users. How intelligent building control helps with this is shown in our topic area.
The Scientific Foundations
The scientific basis for Human-Centric Lighting was only established in the early 2000s. A milestone was the discovery of special photoreceptors in the retina, the so-called intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells were first discovered in mice in 2002 by Samer Hattar, David Berson and colleagues and are particularly sensitive to blue light with a wavelength of approximately 480 nm and are not responsible for vision, but for controlling our internal clock2.
The ipRGC cells transmit light information directly to the suprachiasmatic nucleus (SCN) in the brain, which in turn regulates the production of the "sleep hormone" melatonin in the pineal gland:
- Blue, cool light (high blue content) suppresses melatonin production and promotes the release of cortisol and serotonin → we feel awake and active
- Warm, reddish light (low blue content) enables melatonin production → we become tired and relaxed
These chronobiological findings form the foundation for Human-Centric Lighting. Through targeted control of light parameters, the natural rhythm can be supported – even in indoor spaces where people spend most of their time today.
Biological Effects of Light on Humans
The circadian rhythm – our approximately 24-hour day-night rhythm – is significantly synchronized by light. In nature, the alternation between daylight and darkness serves as the most important for our body. It controls numerous biological functions:
| Time of Day | Natural Light | Body Functions |
|---|---|---|
| Morning (approx. 6-9 AM) | Bright, bluish light | Cortisol rises, melatonin falls, body temperature rises |
| Noon (approx. 12-2 PM) | Very bright, white light | Highest alertness, maximum body temperature |
| Afternoon (approx. 3-6 PM) | Decreasing, warmer light | Slow decline in performance curve |
| Evening (approx. 7-10 PM | Dimmed, warm, reddish light | Beginning of melatonin production |
| Night (approx. 11 PM-5 AM) | Darkness or very weak light | Maximum melatonin release, lowest body temperature |
Through artificial lighting that follows this natural rhythm, Human-Centric Lighting can stabilize the sleep-wake cycle and contribute to the prevention of sleep disorders and other health problems3.
Physiological and Psychological Effects
The effects of light go far beyond controlling the sleep-wake rhythm. Scientific studies demonstrate comprehensive effects on:
- Mood and well-being: Adequate bright light with high blue content can reduce depressive moods and increase general well-being
- Cognitive performance: The right lighting demonstrably improves concentration, reaction speed, and error rate
- Stress regulation: A natural light progression supports the regulation of stress hormones like cortisol
- Regeneration: Adapted evening conditions promote restorative sleep and thus physical regeneration4
With chronic light deficiency or constant exposure to incorrect lighting conditions, there can be an increased risk of various health problems, including sleep disorders, depression, cardiovascular diseases, and even an increased cancer risk (especially with regular night work)5.
The Importance of Light Color and Intensity
Two factors are crucial for the biological effectiveness of lighting: the spectral composition (light color) and the intensity of light6. Learn more about forward-looking circular systems for modern lighting.
The blue content in the light spectrum is particularly relevant for biological effects. Modern LEDs offer the possibility to control this content specifically. The color temperature is specified in Kelvin (K):
- Warm white light (2700-3000 K): Low blue content, relaxing, suitable for evening
- Neutral white light (3500-4000 K): Balanced spectrum, pleasant for extended work
- Daylight white light (5000-6500 K): High blue content, activating, sensible for mornings and noon
In addition to light color, melanopic effective illuminance also plays an important role. It describes how strongly a light source affects the special photoreceptors in the retina. For effective support of the circadian rhythm, melanopic illuminances of at least 250 melanopic lux are recommended during the day7.
An HCL concept simulates the natural daily progression through dynamic changes in both parameters:
- Morning: Bright light (>500 lux) with high color temperature (5000-6000 K)
- Noon: Maximum brightness (500-1000 lux) at neutral to cool color temperature
- Afternoon: Slow reduction in intensity and transition to warmer light
- Evening: Dimmed, warm white light (2700-3000 K) with minimized blue content8
Components of an HCL System
Modern LED Technology
The technological basis for Human-Centric Lighting is modern LED technology. Compared to conventional light sources, LEDs offer decisive advantages:
- Precise controllability of light intensity without color shift
- Almost lossless dimming
- Fast response without warm-up times
- Long lifespan and high energy efficiency
- Compact designs for flexible luminaire designs
Two types of LED solutions are particularly relevant for HCL systems:
- Tunable White Systems combine warm and cool white LEDs, whose proportions can be continuously mixed. This allows the color temperature to be adjusted over a wide range (typically 2700 K to 6500 K) while the light intensity remains constant or can be regulated independently9.
- Full-Spectrum Solutions go a step further and combine multiple LED types with different spectra to replicate natural daylight as precisely as possible. Such systems can optimize not only color temperature but also the color rendering index (CRI) and other spectral properties10.
Control Systems and Automation
An essential component of any HCL system is intelligent control. Modern light management systems make it possible to program and automate complex lighting scenarios. The following functions are important for effective light control:
- Daylight-dependent control: Automatic adjustment of artificial lighting depending on available daylight
- Time-controlled progressions: Pre-programmed lighting scenarios that follow the natural daily progression
- User-defined scenarios: Storable light settings for various activities (concentration, relaxation, meeting, etc.)
- Individual adjustment: Possibility for users to adjust lighting according to personal preferences
- Intuitive operation: Simple user interfaces via wall switches, apps, or voice control
Control can be via various protocols, with open standards such as DALI-2, KNX, Bluetooth Mesh, or Zigbee having established themselves for more complex HCL installations. Increasingly, cloud-based solutions (IoT platforms 2025) are also being used, offering remote access and extensive analysis capabilities
Sensor Technology and Integration
For optimal function, HCL systems need information about the respective environmental situation. Various sensors are used for this:
| Sensor Type | FunctionSignificance for HCL | Significance for HCL |
|---|---|---|
| Presence detectors | Detection of presence and movement | Needs-based activation of the HCL system, energy savings |
| Daylight sensors | Measurement of daylight quantity | Optimal supplementation of natural light, energy efficiency |
| Spectral sensors | Analysis of spectral composition of light | Precise adjustment of artificial lighting to daylight conditions |
| Time sensors | Recording of time and date | Basis for time-dependent lighting scenarios |
| Biomonitoring | Recording of biometric data (e.g., via smartwatches) | Individualized light settings based on health data (future) |
Integration into existing building automation is another important aspect. Modern HCL systems can communicate with heating, air conditioning, shading, and other building functions to realize holistic room concepts.
Application Areas for Human-Centric Lighting
Office Environments and Workplaces
Office buildings are among the most important application areas for Human-Centric Lighting. Here, people often spend many hours daily, frequently without adequate access to natural daylight. The benefits of HCL in this environment are diverse:
- Increased productivity and concentration ability through activating lighting in the morning and after lunch break
- Reduction of fatigue symptoms through biologically effective lighting
- Improvement in well-being and job satisfaction
- Support of biorhythm especially in interior spaces without daylight access
- Optimal adaptation to various work activities (screen work, meetings, creative phases)
A study by industry association Lighting Europe shows that HCL increases the vision, performance and well-being of people, with a 4.5% increase in productivity along with a reduction of 2% in errors and accidents11.
Healthcare and Hospitals
In healthcare, Human-Centric Lighting offers particularly great potential. Both for patients and medical staff, the right lighting can make a significant difference12.
For patients:
- Accelerated recovery through support of the natural biorhythm
- Improved sleep quality through reduced light exposure with blue components in the evening
- Reduced "hospital effect" through more pleasant light atmosphere
- Lower medication needs in some cases (e.g., for pain medication)
For medical staff:
- Better adaptation to shift work through optimized lighting conditions
- Increased alertness in critical situations through activating light
- Reduced error rate in complex medical activities
- Improvement of their own health despite irregular working hours
A recent trial found that circadian-informed lighting significantly improves quality of sleep and work performance for night shift workers. Especially in intensive care units, where patients often lose their day-night rhythm, a well-thought-out HCL concept can support recovery and reduce complications such as intensive care unit delirium.
Educational Institutions and Schools
In schools and other educational institutions, Human-Centric Lighting can positively influence the learning process. The human centric lighting market is experiencing significant growth in educational environments, with schools, universities, and educational institutions increasingly prioritizing lighting systems that promote comfort, health, and enhanced performance. Studies show concrete effects14:
- Higher reading speed and better text comprehension under optimally adjusted light
- Increase in attention span during longer teaching units
- Reduction of restless behavior through mood-stabilizing light
- Improvement of morning alertness, especially in the winter months
Studies showed that students' oral reading fluency improved significantly under optimized lighting conditions, and Dutch investigations have shown that with higher illuminance levels and higher color temperatures, academic performance improves. Lighting can also be flexibly adapted to different learning activities: activating, cool light for exams and concentrated work, neutral light for normal lessons, and warmer, more relaxing light for creative group activities.
Residential and Elderly Care
Human-Centric Lighting is also gaining increasing importance in private living environments and facilities for seniors15.
In the private sector:
- Support for restorative sleep and smooth awakening
- Improvement of domestic well-being
- Promotion of work-life balance in the home office
- Adaptation to seasonal fluctuations (e.g., compensation for lack of light in winter)
In elderly care:
- Stabilization of the often disturbed day-night rhythm of older people
- Reduction of sleep disorders that occur more frequently with age
- Improvement of cognitive performance and mood
- Support for age-related degeneration of the visual system through higher, glare-free illuminance levels
- Potential improvement in dementia diseases through regulation of the day-night rhythm
Studies show that health-oriented lighting in older people can lead to an improvement in sleep quality of up to 43% and a reduction in nocturnal restlessness – an important contribution to quality of life in old age16.
Implementation of HCL Concepts
Planning Aspects and Requirements
The successful implementation of a Human-Centric Lighting concept begins with careful planning. The following aspects should be considered17:
- Needs analysis: Which users will use the room for what and when? What specific requirements are there?
- Daylight analysis: How is the daylight supply in the room? Where are supplements through artificial light necessary?
- Room usage: What activities take place in the room and what specific lighting needs arise from them?
- Lighting planning: What illuminance levels, color temperatures, and light distributions are optimal for the respective areas?
- Control concept: How should the lighting scenarios be controlled? What degrees of automation make sense?
Ideally, interdisciplinary collaboration between lighting planners, interior architects, electrical planners, and if necessary, chronobiologists or occupational physicians is recommended18.
Cost Aspects and Economic Efficiency
Human-Centric Lighting initially requires higher investments than conventional lighting solutions. The additional costs arise from19:
- Special luminaires with adjustable color temperature and high light quality
- More complex control systems and sensors
- Increased planning and programming effort
- Possibly necessary infrastructure adjustments (cabling, control lines)
The human centric lighting market is expected to reach USD 3.6 billion by 2024 from USD 0.8 billion in 2019, growing at a CAGR of 35.2% from 2019 to 2024. These investments can pay off for several reasons:
| Potential Savings | Potential Savings |
|---|---|
| Increased productivity (offices, production facilities) | 1-3 years through 2-5% productivity increase |
| Reduced error rates and reject rates | 2-4 years depending on industry and error criticality |
| Reduced sick leave | 3-5 years through 5-10% fewer light-related absences |
| VShortened hospital stays | 1-2 years through faster recovery and reduced costs |
| Energy savings | 4-7 years through needs-based, sensor-controlled lighting |
Increasingly, more flexible financing and operator models are also being offered, such as "Lighting as a Service," where investment costs are allocated over the operating period.
Integration into Existing Building Infrastructure
Retrofitting Human-Centric Lighting in existing buildings (more about building in existing structures) presents special challenges but also offers opportunities.
Challenges:
- Limited possibilities for structural changes
- Existing electrical installation often not designed for complex control systems
- Integration into existing building automation
- Often limited access to daylight zones
Solution approaches:
- Step-by-step implementation, starting with areas where particular benefit is expected
- Use of wireless control systems that do not require additional control cables
- Retrofit solutions such as replaceable LED modules with adjustable color temperature
- Gateway solutions for connection to existing building management technology
- Cloud-based systems that require minimal intervention in existing infrastructure
Depending on the individual situation, tailor-made solutions can be developed that at least partially integrate the advantages of HCL into existing building structures.
Case Studies and Practical Examples
Intensive Care Unit of a University Hospital
In a pilot project, an intensive care unit was equipped with an HCL system that simulates the natural daily progression – with higher blue components during the day and reduced blue light at night. The results after one year:
- 22% faster regeneration after surgical procedures
- Reduction of intensive care unit delirium by 26%
- Improvement in patients' sleep quality by 31%
- Higher satisfaction of medical staff, especially during night shifts
Care Facility for Dementia Patients
A care facility implemented a dynamic lighting system with a special focus on community areas and corridors. The evaluation after six months showed:
- Reduction of nocturnal restlessness in residents by 38%
- Improved daily structure and activity of residents during the day
- Reduced use of medication for sleep and sedatives
- 15% fewer falls during nighttime hours through better orientation
Medical staff also reported easier care of residents through the stabilized day-night rhythm.
Office Building with Seasonal Light Strategy
In an office complex, an HCL system was installed that not only follows the daily progression but also makes seasonal adjustments. In winter, stronger and bluer light is used in the morning to counteract natural light deficiency.
The results:
- Reduced winter depression and seasonal mood swings among employees
- More consistent performance curve throughout the year
- Positive feedback from employees regarding morning activation in the dark season
The investment costs in this case amortized after just over two years, mainly through the increase in productivity.
Future Perspectives and Developments
Current Research Priorities
Research on Human-Centric Lighting continues to develop dynamically. Current research priorities include:
- Long-term studies on health effects: Investigation of effects over several years, particularly regarding chronic diseases
- Personalized lighting solutions: Individual adaptation to personal chronotypes and preferences
- Optimization of spectral composition: Fine-tuning of the light spectrum for maximum biological effectiveness with simultaneously pleasant visual impression
- Light therapeutic approaches: Targeted light interventions for specific health problems such as depression, sleep disorders, or ADHD
- Cultural and demographic differences: Research into different light needs in various cultural circles and age groups
A special focus is on the quantification and standardization of biological light effects to establish reliable planning parameters for practice.
Technological Innovations
Technological development opens new possibilities for even more effective HCL systems:
- Miniaturization: More compact luminaires with integrated control technology and sensors
- IoT integration: Seamless integration into the Internet of Things for holistic room concepts
- AI-based control: Self-learning systems that analyze user behavior and proactively create optimal lighting conditions
- Biomonitoring: Feedback through wearables and health sensors for individualized light control
- Improved spectra: New LED generations with optimized spectra for maximum biological effectiveness with minimized energy consumption
Increasingly, lighting and building technologies are merging into holistic environmental systems that, in addition to light, also consider and harmonize other factors such as acoustics, air quality, and temperature.
Human-Centric Lighting stands at the interface of technology, biology, and design. It uses our growing understanding of light's effects on humans to create interior spaces that support us not only visually but also biologically and emotionally. The Human Centric Lightings Market was valued at USD 2.27 Billion in 2024, and is expected to reach USD 8.73 Billion by 2030, rising at a CAGR of 25.40%, demonstrating the growing recognition of this holistic approach. In a time when we spend more and more time indoors, this comprehensive approach is increasingly becoming an important factor for health, well-being, and performance.
