Circadian Rhythm - Our Internal Clock | Energy Performance Lighting
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Circadian Rhythm - Our Internal Clock

From the beginning of life on Earth, light has been the catalyst for growth and evolution. It has allowed us to move from single-cell organisms to complex multicellular organisms, sea to land, and four legs to two. It has also ruled when we eat, sleep and how we feel too, way before the clock was invented. This instinct that we go to bed when it’s dark and wake with the sun is actually not an instinct; it is our internal body clock otherwise known as the Circadian Rhythm.

The Circadian Rhythm developed millions of years ago, powered by the light we are living in every day. How our body’s clocks use light is made possible by photoreceptors in our eyes as they input the data from light to tell our bodies what to do. The main two photoreceptors we all know are the rods and cones which help us see colors and movement. There is a third photoreceptor discovered though, the ipRGC (intrinsically photosensitive retinal ganglion cells) which is sensitive to rich blue light that even visually impaired people may be sensitive to. When the ipRGC receives blue light, it is the notification to our brain and circadian rhythm to tell us to be awake, alert, and ready to go.  

Why blue light is an indicator for us to be awake is because of evolution. Over the course of millions of years, our retinas have evolved to associate blue light to daytime. Most light being received outdoors from the sun is blue light, which is why our body associates it with being awake. When blue light strikes our retinas during the day, a signal is sent to produce cortisol, which is the hormone that gives us the feeling of alertness, pleasure and stress control.

When we aren’t being exposed to blue light, after about half an hour, our body switches over to producing the hormone, melatonin. Melatonin and cortisol hormones are the balance between day and night, allowing for us to be alert during the day and calm, rested and recovering during the night. Having the balance between cortisol and melatonin is crucial to having a proper circadian rhythm, which has proven to be needed for a healthy life. With a disrupted circadian rhythm, which comes from an unbalance of not enough blue light or too much blue light, there can be consequences. For many people, they may have elevated health risks or they may be feeling crabby, depressed, have bad coordination or just find it hard to think.

Some big reasons why people have disrupted circadian rhythms may be because of the shift they work or the environment they work in. For people who work third shift, they have their circadian rhythm flipped upside down with their nights being their days and their days being their nights. The environment people work in too can be a huge factor, day or night. On average, Americans today only spend 7% of their day outdoors or about 1.5 hours a day. So if you are indoors for work, and aren’t getting your need of stimulating blue light from the overhead lights, you could have a disrupted sleep cycle. This is because you aren’t having the stimulating light during the day.

At EPL, we design and install lighting systems that work to improve the quality of lighting in your business as well as promote health and wellness.  We work to optimize the space for your needs, and for the employees, students and patients who occupy the space, all while giving you an amazing reduction in energy costs.

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