The IoT and human-centric lighting

Better light, better life. That's the principle behind human-centric lighting, a range of evidence-based solutions that illuminate the way to better health, brighter moods, sharper focus, and heightened alertness.

Human-centric lighting is a matter of sophisticated research, and is increasingly informed by Internet of Things (IoT) approaches that enhance its capabilities, but it grew out of homespun wisdom. Tell someone you're feeling ill or run down and you're likely to be advised to get outside more — to get more light.

And it's not just about vitamin D. Light in the blue range of the spectrum helps your body tell time and stay aligned with circadian rhythms, the natural 24-hour cycle of sleeping and waking. Soft, dim light helps spur creativity, while brighter lights can help our mood and ability to focus, even to the extent of shortening depression-related hospitalizations. And that's why lighting systems that are good for people beyond just their ability to banish darkness (as important as that ability is) are taking center stage.

These priorities aren't just for a select few high-tech corporate headquarters either. The WELL Building Standard defines 13 lighting design categories that promote better health and well-being everywhere from offices to homes. The guidelines call for mandatory glare reduction, lighting patterns that protect circadian rhythms, and an emphasis on color quality, not just on brightness.

The WELL standard also defines what it calls the Right to Light for all, a state in which 75 percent of all regularly occupied spaces are within 7.5 meters of a window and all workstations are within 7.5 meters of a window or atrium. Those are conceptual building blocks any architect or designer can get behind. And studies find that the slightly higher energy costs of human-centric lighting are offset by productivity or wellness measures like reduced sick days and lower healthcare costs.

You might associate human-centric lighting with the responsive conference room that adjusts luminaires automatically based on the preferences of the presenter or audience, or even on the meeting's theme. But tunable light does much more than add a little flash and mood to the workplace.

Using hidden IoT sensors in a room to pick up on changes in vocal stress patterns, light can actually respond to promote relaxation when tensions run high. If the heat and humidity spike in a room, the lighting system can shift to provide a "cooler" light that will have a salubrious emotional effect on the room's occupants. Lighting can be adjusted so that it creates discrete illuminated zones in which people can cluster, in that way promoting collaboration; or it can be deployed in wide-angle patterns to encourage unhindered wide-scale thinking. Bright and varied lighting effects that attract people can create a 21st century water cooler or town square experience, safely promoting natural congregation and exchange.

By tuning whites and adding accent colors, interior lighting can be programmed to change over the course of the day in a way that mimics the effects of the daylight outside. Such lighting would feature gradually increasing illumination as the day dawns, thus stimulating the production of cortisol, the “stress hormone" that promotes wakefulness; then it would dim as bedtime approaches, stimulating the secretion of melatonin, the hormone that helps us sleep. This would help people maintain smooth circadian rhythms and a connection to nature even if (like most of us) they spend most of their time working and living indoors.

Tunable light can also promote different activities and atmospheres, adding more blues to the mix for higher energy and focus, or more ambers and reds to help people decompress. IoT sensors can pick up gestures, respond to voice commands, or synchronize with a personal calendar to establish the right illumination for the task at hand, or to help prepare the space's occupant for the next big thing on the day's agenda. Wearables can even enable lighting to automatically respond to biometric data.

Human-centric lighting is making an especial difference in settings where we seek to heal, or to better, ourselves. In hospital settings, tunable light systems are already promoting better sleep, which is key to patient recovery. In education, students are benefiting from the greater cognitive focus that the right lighting regime promotes.

As human-centric lighting becomes more common, people will learn to use illumination to signal a need for assistance or a desire for company — or, conversely, to be left alone. "Status lights" will help us stake out personal space without using walls, and to invite or exclude as we require — or as our wearable sensors detect would be best for us.

The next wave of human-centric lighting will arrive as researchers learn more about how light affects us beyond the 24-hour internal clock. Biologists have also found surprising interactions between light and body processes as they unravel the mysteries of cryptochromes. These are proteins that respond to visible light or other radiant energy, and they're at the core of so-called extra-ocular vision, the body's response to light beyond the normal process of vision. In short, cryptochromes help plants and animals respond to light in ways not associated with sight.

The most carefully studied cryptochrome, melanopsin, is found in several plants and animals. It can be found in the ganglion cells of the human retina, the first light-sensitive components of a baby's eye to start functioning.

Many such cells disappear in the weeks immediately following birth, which limits the opportunity to study them. But we do know that melanopsin-carrying ganglion cells are part of the reason congenitally blind individuals will respond to the presence of light on both a conscious and an autonomic level. (These cells' existence explains why a pupil will still react to light even when the eye is totally devoid of the rod and cone cells that make vision possible.) And we know that cryptochromes help some animals perceive and process light outside the visible spectrum. In some bird species, cryptochromes power the natural magnetic compass that guides flight and homing. Other research has found a link between melanopsin and cognitive ability in mice, and a connection between melanopsin and cardiovascular health.

As this research bears fruit and more long-term studies of the benefits of human-centric lighting take shape, we may find that lighting eventually becomes just as personal as clothing, and as precisely calibrated as an athlete's diet. Lighting, in fact, is an ideal component of the quantified self movement. Using biometric data and tunable light, each individual could devise a regime according to which he or she is followed throughout the day — at home, at work, and in transit — with the healthiest possible personal lighting environment.

The study of non-visual photoreception is new, but it's already showing its potential to brighten our lives. As research into it intensifies, its possibilities will grow, letting us make the most of a phenomenon that we're coming to realize is as important to our well-being as air, water, and food.