Light brings buildings to life. It can make a space look expansive, intimate, playful, or luxurious. A beautifully lit space can induce a state of awe. Thoughtful lighting can inspire us to walk around and explore, to engage with one another, or to slow down and relax.
However, the influence of light extends far beyond supporting vision. Our ancestors spent most of their waking hours under the open sky, and over the course of history, humans have evolved to respond to even the most subtle variations in light. Although we are not always conscious of its impact, light affects our biological, emotional and cognitive functions. It regulates our sleep cycles, affects our mood and mental health, shapes our behaviour, and influences our decisions.
Quality lighting can help us function at our best, whether we work, explore opportunities, tackle problems, connect with others, play or rest. In workplaces, the right lighting can support focus, boost productivity and foster creativity. In retail environments, it can influence customer behaviour and sales. In hospitality venues, it plays a crucial role in creating memorable experiences that keep guests coming back.
Light also shapes conversations. Harsh, bright light can evoke a more formal and restrained discussion, while soft, dim ambience can encourage a more relaxed and personal exchange. When the lighting in a room suddenly changes, perhaps by flicking a switch or closing the blinds, the tone of the conversation can shift just as suddenly.
Poor lighting, however, can make us uncomfortable, tired, and eager to leave. On the long term, inadequate lighting conditions can lead to serious physical and mental health issues as well as performance challenges. People spending most of their working hours in poorly lit spaces often find that their quality of life is seriously impacted.
Despite this knowledge, lighting systems in buildings are often designed by focusing on a narrow range of metrics – including visibility and energy efficiency – while overlooking the broader aspects of human health and experience. Standards are evolving more slowly than our scientific understanding of the intricacies of light, and the ways buildings are experienced and used today. As a result, many buildings – while ticking all the boxes of old-school requirements – fail to genuinely serve the needs of people and organisations.
While natural light is the most valuable form of light for humans, it inevitably needs to be complemented with artificial lighting to ensure optimum lighting in all areas, during all hours of operations. Due to evolving lighting technologies, high quality lighting can be achieved even in spaces with insufficient daylight.
To harness the power of human-centric lighting, designers and decision makers need to take into consideration the broad range of attributes of light that influence human experiences and outcomes. Some of the most important ones are listed here.
Seven dimensions of light
1. Lighting colour: Aligning with natural rhythms
As the day progresses, the colour of sunlight shifts – starting with a warm, golden hue at sunrise, transitioning to a cooler, bluish-white light during the day, and returning to a warm, amber tone at sunset. This characteristic of light is known as colour temperature. The human body has evolved to synchronise with the natural cycles of light through the circadian rhythm, our internal clock that regulates alertness, sleep, metabolism, hormone production, and other biological functions.
Warm light in the evening, on the other hand, helps us relax and prepares the body for sleep. Exposure to warm light has also been found to soothe feelings of anxiety or tension, and promote open-mindedness and abstract thinking – supporting creative problem-solving. Additionally, warm light can positively impact human relationships by encouraging openness and trust, supporting social bonding, and fostering a greater sense of psychological safety.
While warm and cool lights both have inherent benefits, exposure to the wrong types of light at various points during the day – for example, viewing warm light in the middle of the day or blue light late in the afternoon or evening – can disrupt our circadian rhythm. The immediate consequences may include fatigue, cognitive impairment, low mood, sleep problems, and reduced immune function. Prolonged disruption can also lead to mental health issues, metabolic and hormonal disorders, weight gain, and an increased risk of cancer.
Most buildings are equipped with luminaires that emit the same colour of light throughout the day. When people spend most of their days under this type of artificial light, they likely experience disruptions to their biological rhythms, which can put their health, wellbeing, and performance at risk.
Thankfully, dynamic lighting systems are available that adjust colour temperatures throughout the day, mimicking natural light patterns. While these systems are more expensive to implement than traditional lighting, their positive impact on people and businesses should not be underestimated.
2. Lighting spectrums: The invisible impact
Natural light contains a full spectrum of frequencies, including invisible infrared (IR) and ultraviolet (UV) light, each playing crucial roles in human health. Infrared light supports cellular energy production, enhancing cognitive performance and metabolic health. Ultraviolet light is essential for vitamin D synthesis, which supports bone health, immune function, and mental wellbeing.
Most artificial luminaires are designed with a sole focus on visible light, and largely lack the invisible frequencies found in natural light. Standard LEDs, while energy efficient, are particularly problematic in this regard. With professional workers spending most of their waking ours indoors, this deficiency may contribute to a range of health issues, including osteoporosis, autoimmune diseases, mood disorders, and accelerated aging.
Thankfully, lighting products that more closely replicate the frequencies of natural light are available – including broadband spectrum LEDs. Investing into such solutions can not only enhance human wellbeing and performance, but also lead to improvements in public health.
3. Brightness and darkness: Beyond visual comfort
In alignment with the natural cycles of the day, bright lights are energising while dim lights are typically more relaxing. However, lighting levels have many other fascinating effects.
Research suggests that under bright light, people tend to perceive a room as physically warmer, express themselves more passionately, and judge other people’s behaviours differently, compared to darker spaces. Bright lights can also make it easier to engage in activities requiring deep concentration.
In dim lighting, on the other hand, people may feel less constrained by risks or restrictions, and be more inclined to explore and express creative ideas. (In one paper, researchers conclude that adjusting lighting levels in trading environments – and consequently altering people’s willingness to take risks – could ultimately influence market volatility.)
Lighting levels play interesting roles in hospitality and retail settings as well. In brightly lit restaurants, diners may make healthier food choices, and consume food faster, compared to dimmer settings. In stores, customers tend to examine products more carefully under brighter lights.
Despite these nuanced effects, lighting levels are often specified with a narrow focus on visibility, which can lead to poor user experiences and business outcomes. Sometimes large sections of buildings with a variety of functions have uniform lighting levels. Certain types of spaces are notoriously underlit. When office workers find themselves drifting off during meetings, low lighting levels might be a likely contributor. Conversely, excessive lighting levels in social environments could kill intimacy.
To create spaces that serve their purpose effectively, designers should consider how each area will be used, how lighting levels influence mood and cognition, and what age groups users belong to. (As the eye lens darkens with age, older people require significantly more light to see well.)
4. Colour rendering: The truth in light
Colour rendering – an attribute of light sources that describes how accurately they show colours – strongly impacts how we perceive spaces, objects, and even people. In retail settings, for example, high colour rendering can create an inviting atmosphere, make products appear more attractive, and increase shoppers’ range of browsing – as shown by research. In healthcare settings, accurate colours are essential when evaluating patients’ conditions.
Unfortunately, in many buildings – including most workplaces – lighting is designed with little attention to colour rendering. Many office workers are familiar with the experience of talking to colleagues whose faces appear in yellowish or greenish hues. In such unnatural environments, connecting with people, reading their non-verbal signals, and empathising with their feelings can be more challenging.
The power of colour rendering should not be underestimated in any environments where first impressions count and where the quality of interactions with people or products is important. Accurate colours are not only aesthetic considerations, but also a matter of communication, human experience, and business performance.
5. Direction of light: Creating a natural ambience
Under the open sky, during the day, light surrounds as all around. From horizon to horizon, the entire sky illuminates in bright blue and white. Most modern buildings provide a vastly different ambience. As building standards and regulations primarily focus on lighting levels on horizontal surfaces such as floors and desks (as if people today spend most of their time looking at papers or factory machines), ceiling mounted downlights have become a prevalent lighting feature in the commercial and retail landscape.
In the absence of additional ambient lighting, downlights tend to leave the ceilings and walls relatively dark, leading to a ‘cave effect’. (Dark ceiling colours only make this effect worse.) This unnatural light distribution is a common cause of discomfort, eyestrain, and drowsiness. Downlights can also create unflattering shadows on faces, which are not only disruptive for face-to-face conversations but also for videoconferences.
Lighting designers need to look beyond regulations rooted in a past era and pay greater attention to human experiences and behaviours. It’s important to remember that our visual system is primarily oriented towards vertical surfaces, and that spaces with illuminated walls and ceilings often feel more welcoming and natural.
By incorporating ambient lighting, using diffuse light sources, and illuminating spaces from multiple directions, designers can create more comfortable and appealing environments that support positive experiences and higher performance.
6. Variations and contrasts: The art of layering light
The thoughtful use of light and shadow helps define spaces, create a unique and harmonious atmosphere, and strengthen brand identity. Subtle variations in lighting levels and effects – mirroring the dynamic qualities of natural light – can enhance wellbeing and cognitive performance.
Variations in lighting also directs attention and shapes user experiences. In retail environments, it can guide customers through the space and highlight key products. Research suggests that the effective combination of ambient and accent lighting can influence shoppers’ mood, behaviour, and perception of product quality.
In hospitality settings, layered lighting can help create a welcoming ambience and support social interaction and relaxation. In workplaces, combining various lighting solutions can define functional zones and enhance the versatility of spaces while supporting visual comfort.
Yet, many interior spaces either lack meaningful variations in lighting or create glare through strong contrasts. Effective design strategically integrates different lighting types – such as ambient, task, accent, or decorative lighting – to create environments that are both engaging and comfortable.
7. Lighting controls: Personalising the user experience
People have vastly different needs and preferences for lighting. One person may find a space too dark, while another finds the same spot too bright. (In workplaces with operable blinds, this is a common cause of dispute among employees.) In many buildings, achieving comfortable lighting for everyone without user control can be very difficult – sometimes even impossible.
Providing occupant-controlled lighting systems often seems a complex and costly challenge. Many modern buildings offer little or no control to occupants, which can lead to lower satisfaction levels. However, even limited control over lighting can significantly improve people’s experience. In one study, an interactive system that gave users a perception of control increased satisfaction just as much as a system that offered full control.
Modern lighting systems can integrate automation with user control, using features like presence sensors and personal overrides. This approach is particularly valuable in spaces that require versatility and adaptability. In workplaces, for example, a space may be transformed from a formal meeting area to an innovation hub or a relaxation zone at the press of a button. In a restaurant or a hotel, a space may be transformed from a formal lounge space to a social entertainment venue. The possibilities are endless.
From adequate to exceptional: The business case for better light
In many ways, light is like the air we breathe – we rarely notice it consciously, but our bodies and minds respond to it immediately. When it’s high quality, we feel physically and emotionally better, and we think more clearly. When it’s poor quality, we feel unwell, struggle to focus, and find it harder to function or enjoy what we do.
Air quality is continuously monitored in buildings, with alarms triggering immediate action when standards are not met. While lighting may not always demand the same urgency, it certainly deserves far more attention than it currently receives. Just as we wouldn’t consider clean air luxury, we shouldn’t settle for lighting that is merely adequate for vision.
Designing effective lighting is a complex task that requires expertise in both the technical properties of light and its biological and psychological effects on humans. Thoughtful design considers multiple factors, including the purpose of the space, the needs of its users, the available natural light, architectural features, environmental impact, and business objectives.
The profound impact of lighting on human experience and behaviour is well documented, yet design teams often prioritise upfront costs and energy efficiency over lighting quality. It’s essential to recognise lighting as a key driver of human health, performance, and engagement – and to acknowledge the significant returns that thoughtful design can deliver. Investing in better lighting solutions can lead to substantial short- and long-term benefits, from higher productivity and enhanced wellbeing to growing sales and improved business outcomes.
High quality lighting, beyond optimising vision, has the potential to elevate lives and transform organisations.
