A healthy recipe for lighting has been proposed by longtime advocate of light as part of well-being, Mary Rushton-Beales, who says architects and employers need to create healthier workplaces, based on providing a balanced ‘diet’ of light and darkness
We have evolved to respond to a natural cycle of light and dark, day and night, that changes gently but dynamically over time. But in our very recent history we have deliberately ignored these natural rhythms and we expect our bodies to cope with instant and prolonged high levels of artificial lighting. It is like fast food: many of us are getting the wrong light, at the wrong time. We need to think about the amount and quality of light we need and avoid bingeing on it.
We need a varied diet of light. We have all been swept along by the energy efficiency of LED lighting and there is a tendency for clients to demand all-LED lighting solutions. But they do not produce the full spectrum of natural light and are not suitable for every application. You need balance, variety and a range of techniques in lighting, just like you do with cookery.
Recipe for healthy lighting
Drawing on a wide range of research, Lighting Design House has developed a recipe for healthy lighting. Like most recipes, it relies on timing for its success. This means matching the quality and amount of light both with your mood and with the physiological needs dictated by your body-clock. The key ingredients are a big fat dollop of darkness, a few pinches of brightness, several swirls of visual comfort, season with visual delight.’
Balance of ingredients and techniques
Visible light has a number of ‘ingredients’ that can have a positive or harmful effect on us, Rushton-Beales explains. ‘The natural light that we can see combines all the different wavelengths of light from ‘warm’ red through to ‘cold’ blue and ranges in intensity from strong sunlight to weak moonlight. The intensity and colour temperature of light, how long we are exposed to it and whether our body-clocks are telling us to be active or to rest are all linked.
As well as sending information along the optic nerve, which the brain translates into what we see, the also eye sends non-visual messages to the part the brain that houses the body-clock. That keeps us tied to a 24-hour or circadian cycle and stimulates or suppresses hormones for sleep, running our immune systems and controlling our ability to metabolise food.
Research has shown that you can stimulate the brain when it wants to rest, using a bluer, cooler light to increase alertness, much as you might perk yourself up with a coffee, but that is not good for you in the long run. And we know, now, that people who work the night-shift for a long while can end up with health problems.
YOUR PERSONAL LIGHT DIET
• A big fat dollop of darkness
• A few pinches of brightness
• Several swirls of visual comfort
• Season with visual delight
TIMING, CONTENT and CONTEXT
• Allow your eyes to adjust from full darkness before opening curtains or allowing daylight to enter the space and before checking lit devices such as a tablet or phone.
• Slowly increase the amount of light using selective switching dimming or blinds/sheers/curtains on
• Consider simple changes such as brighter light in the bathroom or kitchen when getting ready to go out.
• If you are tired, give your eyes and body longer to adjust to the morning.
• Get some bright light – ideally from a 20‐minute walk in daylight. If that’s not possible, use artificial light.
• Ensure background light is balanced for visual comfort: not too much contrast between ‘task information’ such as notes and your screen.
• Ensure that background light is of suitable brightness for the task. If not, increase light locally.
• Vary your lit environment during the working morning – brighter or dimmer – walk to get a coffee; focus on different tasks for a few minutes, enjoy the view.
• Get some bright light – ideally from a 20‐minute walk in daylight – otherwise use artificial light.
• Vary your lit environment.
• Repeat morning work ingredients: a balance between task and screen; the right light for the task, and moving around to get plenty of variation in light levels.
Early evening leisure
• Get some bright light – ideally a 20‐minute walk in daylight – but if not, use artificial light.
• Ensure background light is balanced for visual comfort and of suitable brightness for the type of leisure activity.
Late evening leisure and rest
• Gradually reduce background light using selective switching dimming or blinds/sheers/curtains on
• Turn off hand‐held devices.
• ‘Wind down’ in low light levels that do not stimulate the body clock.
• Full darkness – ideally using curtains rather than an eye mask