Circadian Rhythm and LED Lighting: What Should OEMs Know

By Roger ElliottJuly 26, 2017

Light, as we all know, enables us to see the world in its rich color and vivid detail. But, what it also does is control our biological responses that make us active during the daytime and sleepy at night. The daily changes in our mental and physical behavioral states, due to the light-and-dark cycle, is scientifically known as the circadian rhythm.

How Light Affects Our Circadian Rhythm

Over the past 25 years, studies have revealed, how the circadian system evolved in order to optimally time the physiology and behavior of organisms to the environmental periodicity correlated with the earth’s rotation. Since the period, or cycle, in most organisms is close, but not accurately 24 hours, the circadian rhythms must be 'entertained' to the 24-hour-day on a daily basis. This process is usually achieved through exposure to light and darkness.

Earlier, many study reports suggested that human circadian rhythms were different from other organisms, being almost insensitive to light and more receptive to social cues. However, consequent re-analysis of previous studies have shown that humans are as sensitive to the intensity of light as any other diurnal beings. Subsequently, the effects of light on the human biological system were carefully reviewed from the late 1950s through the 1970s. 

Research works in the early 1990s led to the discovery of intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina. These cells, if they don't receive the spectrum of daylight for two hours, start to secrete a hormone called melatonin that triggers the circadian or sleep cycle.

Most of us, today, spend almost 90% of our time indoors in artificial lighting environment, often gazing at our tablets, smartphones, TVs, computer screens, or laptops for several hours. This essentially means, our connection with the outside world is lost, and with it, the natural daylight that controls our biological system.

These devices, with self-luminous displays, typically emit a short-wavelength or “blue” light that is melatonin-suppressive during the night time. The artificial light emitted from these gadgets trick our brain into thinking that it is daytime, and we should be active, vibrant, and alert to handle anything. This disrupts the sleep cycle and destabilizes the circadian rhythm.

Evidence evolving from various research does reflect that exposing ourselves to harmful blue light for extended periods can be extremely dangerous. Multiple studies reveal that messing with the sleep pattern can lead to health problems including heart disease, ulcer, diabetes, and even cancer. Nevertheless, research also indicates that the blue light intermixed within the spectrum of sunlight isn't bad, rather, it elevates our mood and visual experiences while restoring a healthy circadian cycle.

Why Lighting OEMs and Designers Should Know About Circadian Rhythm

Research on circadian rhythm has allowed OEMs to understand how selection of different light colors and intensities can effectively change the look and atmosphere of any room and adjust it to suit every situation and occasion. For instance, intense colors can turn an event into a memorable affair; cooler light creates an atmosphere where mental performance and vigilance is enhanced, while warm light such as red and orange colors encourage relaxation.

Being able to mimic the spectral quality and continuous color temperature changes of sunlight throughout the day is allowing OEMs to create lighting solutions perfectly synchronised with the circadian rhythm. This type of human-centric lighting is playing major roles in improving health by mitigating circadian disruptions.

Case in point: the brain trauma ward at Aarhus University Hospital in Denmark, which is utilizing a circadian lighting system to help patients recover faster. According to a Harvard University mental health letter, 50-80% of psychiatric patients suffer from a circadian disorder, which reduces the effectiveness of their medicines and other treatments. After installing the circadian lighting system, the Denmark hospital is witnessing better resting patterns, less stress, and improved healing among its patients who have suffered brain traumas. Among other benefits, the night shift workers at the hospital have reported better sleep quality during their daytime slumber hours.

Educating yourself on circadian rhythm and how different light colors and intensities can effect the atmosphere of a room should be a top priority for lighting OEMs. To learn more about how WPG Americas can assist you in desiging your lighting products, contact us.