It’s the middle of the night and you are strolling through a street of offices, shops, or even passing through a mall and depending where you are and how safe it is a common feature no matter where you are which we have got used to is seeing security guards on that lovely office chair tossing and turning enjoying their sleep. Or mysteriously visit a hospital ward in the middle of the night and see nurses fast asleep because hey all the patients are asleep as well right? Don’t be confused to think that it’s the comfort of the chair that makes them sleep because even on the hardest of surfaces like a concrete slab they will still sleep. Incompetent? Hold your conclusion and let me explain, they are behaving like that because they are not in sync with the Circadian rhythm known as the internal human clock that determines when to be awake and when to fall asleep. The circadian rhythm is known to rely on Intrinsically Photosensitive Retinal Ganglion Cells (ipRGC) that rely on light to kick-start the body or prepare it for shutdown and has developed over millenniums and mankind have adapted to it. One person’s response is to think that the sleeping beauties don’t take a nap during the day and that’s why the sleep at night but believe me I know they sleep, my mother is a practicing nurse and I grew up seeing her sleeping all day and still feel sleepy at night.
Let me explain how this comes about, with a normal circadian rhythm when you wake up in the morning and look at that watch and exposed to light (artificial or natural) you secrete hormones that ensure that you are ready to be active for the day ahead viz;
- Dopamine: Secreted for muscle coordination and pleasure;
- Seratonin: responsible for carbohydrate craving and impulse;
- Cortisol: responsible for stress response.
For a long time, people used to spend over 80% of their time outdoors working or relaxing and the cycle of the sun really shaped the human clock we have called circadian rhythm. These days we spend 90% of our time indoors depending on your job type and it takes a lot of adaptation to keep your body as active. Lighting experts have come up with innovative ways of ensuring that the body will not notice the difference and the concept of designing that lighting is called “Human Centric Lighting”. It is defined by Lighting Europe as a type of lighting that can benefit the biological, emotional, health, or well-being of people.
Intrinsically Photosensitive Retinal Ganglion Cells (ipRGC) respond very well to light that is rich in the blue content, for example, a beautiful sky-blue mid-day is rich in blue light giving off 10 000K of light quality. With reduced color temperature, the body produces melatonin which enables sleep and allows the body to regenerate. When the light Is taken away or reduced, the body automatically starts the process of shutdown. Blue light encourages the production of dopamine, cortisol, and serotonin and this has been proven to make the muscles more active whether you are indoors or outdoors. Given that we now spend 90% of our time indoors it is necessary today that we be very conscious of the type of lighting we have indoors so that it does not go against the circadian rhythm.
The South African Bureau of Standards (SABS) has laid out standards on the quality of light and the type of luminaire appropriate in any type of space through standards SANS 1277, SANS 1279, SANS 10225 and SANS 61547. Many buildings owners have gone to ensure that the lighting standards for their inhabitants who are indoors for longer periods of time receive the proper lighting to ensure maximum productivity during their working hours. Proper task specific lighting ensures that the working space is visible, reduces the risk of accidents and gets the work done, meeting production goals and ensuring that they stay in business. The ability to alternate the lighting levels to set the mood of any space was not what Russian scientist Oleg Losev had in mind in 1927 when he discovered the first LED and the technology has since evolved. Today you can modify lighting levels by setting the color temperature between warm and cool white temperature.
There are 2 types of color temperatures viz; warm white and cool white and just in case you are wondering what all this is, I assure you it has been around you all the time.
Warm White: Remember those Incandescent lights we used to have years ago, that produced a lot of heat and have an orange color. They are classified as warm white and the orange color is dominated by the red and orange spectrum of white light spectrum in their composition. In nature, you see warm white at dawn when the horizon looks orange and author Roman Payne captured this in his book Wanderess, “Ô, Sunlight! The most precious gold to be found on Earth.” Another example of white light is the old street lights that have that orange appearance or in a parking lot and if you put your hand under the light, the image is not as good and you can barely see your hand well enough.
The second color temperature is called cool white and contains a lot of blue light spectrum and this is a typical blue sky mid-day appearance. This color temperature is known to enhance performance and experiments have been conducted whilst varying the degree of cool light from 4 000K to 10 000K and see how people respond. Studies have shown that people are more active and awake with cool white light and can be used to assimilate a typical sunlight indoors. This is because the high concentration of blue light stimulates photoreceptors that will cause the pupils of the eyes to become smaller and a person can see more clearly. If you have a CFL that works very well or an LED, it emits a cool white color and things appear distinctively
When you walk into a restaurant, you are greeted with this dim light that ensures that you become relaxed at the same time a laboratory or examining room requires cool bright white light because you want all the details to be visible and cool white light does it. When designing, any space be it a factory, office, bedroom, study room, kitchen, restaurant or your kids’ playroom bear in mind that you can use color temperatures to set the mood before any person walks in. All this is possible by utilizing the LED lighting technology since its onset in the lighting space LED has given people the power to control their lighting levels efficiently. Now if you use an office that has glass walls and sunlight is coming through and lighting up the space but maybe not enough, you can supplement that with artificial light and when the sunlight is going down the balance is provided by the lights and you can maintain a specific ambience in the office or floor space and this is called Daylight Harvesting.
Auditoriums, classrooms, and libraries do not need to worry anymore about having a constant brightness 24 hours a day but by using the dimming technology you can increase and reduce the brightness to suit the time of day and function of the room. Since this was an introduction to lighting, in the next feature we will go a bit further and explore what kind of lighting we have been using and what this LED and CFL technology have to offer. How unique are they and why you should consider them the next time you are ordering fluorescent lights for your company or walk into a store seeking to replace a blown light bulb or tube.
Collins Nyamadzawo is an Energy Engineer and Philips LED Certified Specialist. For your views and comments, he can be reached on firstname.lastname@example.org