Christine lives in a small studio apartment. Every morning she wakes up using an alarm clock that has a light that simulates the rising sun. The clock’s slowly increasing level of light gently wakes her up, so that by the time she turns on the apartment’s bright white lights she already feels refreshed and ready to go. Even in the bathroom, Christine uses a mirror with bright white lighting and special high-colour rendering that not only helps her put her makeup on, it also energises her.
Every living creature is controlled by an internal clock. Ours is telling our bodies when to wake up, when to sleep – and everything in-between. Called the circadian system, it regulates the production of different hormones throughout the day, each of which influences a different action. Using a bright white light in the morning helps us synchronise our circadian system with the day.
Although Christine leaves her house feeling energised, the poor lighting in the subway that she takes to work quickly dampens her mood.
Lighting influences your mood, it also helps keep you safe. For instance, in the subway, good lighting makes it easier to see such dangers as the gap between the carriage and the platform.
Christine sits in the office. The office’s open plan layout with ample natural lighting and bright white electric lights energises the staff. To further increase productivity, every employee is being given a desk lamp that they can adjust to their individual lighting preferences.
Bright white light early in the morning helps us synchronise our internal clocks, making us feel more active and less stressed. But at the end of the day, these lights have the opposite effect, keeping us awake by up to 3.5 hours. That’s why we need to switch to a dimmer, warmer light at least two hours before bedtime.
Our bodies require eight hours of sleep to fully recover from the day. This amount of sleep also increases our long-term memory, creativity, and problem-solving abilities – along with making us more social.
Christine is giving a presentation on how light affects people and productivity. She has made sure that the meeting room’s lighting is properly adjusted. Setting the light management system to ‘presentation’ mode, the lights in front of the screen are dimmed for optimal visibility. The rest of the room is lit with white lighting, which ensures that the participants remain awake and engaged throughout the presentation.
The Nobel Prize in Physiology or Medicine 2017 was awarded jointly to Jeffrey C. Hall, Michael Rosbash and Michael W. Young "for their discoveries of molecular mechanisms controlling the circadian rhythm". The team’s discoveries helped to explain the mechanism by which light can synchronise the 24-hour body clock.
A circadian rhythm is any biological process that displays an endogenous oscillation of about 24 hours interacting with the environment.(https://en.wikipedia.org/wiki/Circadian_rhythm) These 24-hour rhythms are driven by a circadian clock, and they have been widely observed all living species. The rhythm is linked to the light–dark cycle. The environmental cues that reset the rhythms each day are called zeitgebers (from the German, "time-givers")
During their lunch break, Christine and her colleagues decide to go for a short walk outside.
Even a 15-minute walk outdoors after lunch can help you getting over the typical fatigue after a meal.
Even on a cloudy day, you can get up to 10,000 lux when outside, whereas in an office you will typically only get 500 lux.
After work, Christine meets a friend for dinner at her favourite restaurant. Talking about her morning presentation on lighting, Christine notes how the restaurant’s dimmed lights and the warm light above the table helps create a relaxed atmosphere for enjoying their food.
Back home, Christine maintains this relaxed atmosphere by only turning on a floor lamp and dimming the bathroom light as she gets ready for bed.
Because there isn’t always daylight when we need it, sometimes we must mimic it using electric lighting. With the right amount, timing, direction and spectral quality, electric light can have a similar effect on our circadian rhythm as natural light.