Circadian Lighting

“Students exposed to lighting with higher light intensity and light temperature levels had, by the end of the year, increases in performance that were 33% higher than the increases in performance of the control group.”

- Human Centric Lighting, Stan Walerczyk, CLEP, LC

We are entering the next stage of lighting that is characterized by the myriad of benefits advanced lighting can provide beyond simply light and energy savings. The term that has arisen to account for these advanced capabilities is Human-Centric Lighting (HCL). HCL is used to describe lighting that, considering both visual and non-visual effects of light, aims to enhance the biological and emotional health and well-being of people.

One of the more advanced subsets of HCL concerns our circadian rhythm, or the body’s process for regulating the sleep wake cycle. Circadian lighting is, in effect, an artificial sunrise to sunset that travels through the color spectrum (for EnFocus™, from 2,700K to 6,500K) and illuminance levels. As the primary stimulus for regulating circadian rhythm, light has a remarkable capacity to influence well-being.

In the classroom, producing light with cooler, bluer color temperatures and higher intensity, mimics the sun’s daylight quality that induces dopamine, endorphins and cortisol while suppressing melatonin, which can promote higher visual acuity and mental focus, according to several studies. Towards the end of the day, lowering color temperature and dimming the light mimics the color spectrum during sunset, prompting calmer moods by inducing melatonin.

Constant electric light is one of the key factors that affects how well we sleep. Evening blue led light has twice the harmful impact on nighttime melatonin suppression than warm yellower light, even at the same light intensity. [“The Dark Side of Modern Light.” Why We Sleep: Unlocking the Power of Sleep and Dreams, by Matthew P. Walker, Scribner, an Imprint of Simon & Schuster, Inc., 2018, pp. 265-270.]

Sleep is inextricably linked to cognitive development, so schools have a vested interest in promoting healthy sleep. Research published in Brain and Cognition has demonstrated that the frontal lobe, which enables rational thinking and critical decision making, requires deep sleep to accomplish the neural maturation required for proper development during adolescence. Students exposed to circadian lighting throughout the day should be able to sleep better at night, according to research in Neuroendocrinology Letters, which can be a powerful tool for learning. In fact, studies have demonstrated significant improvements in learning efficiency and test scores under circadian lighting, including a study of elementary school students conducted by University of Mississippi showing a 33% increase in performance under circadian lighting compared with the control group.

Quality sleep is also critical for immune health, with recent research showing that the disruption of the biological circadian clock leads to a dysregulation of immune responses. Reinforcing the circadian rhythm of high-risk people, in hospitals for example, may boost immunity and prevent hospital-acquired infections. Numerous studies have demonstrated an increase in the morbidity risk of cardiovascular disease, metabolic disease, and cancers from the disturbance of one’s circadian rhythm.

Additional research found that individuals obtaining insufficient sleep in the week before receiving the influenza vaccine produce less than 50% of the normal antibody response. Thereby rendering that vaccination significantly less effective. Sleep effectively restocks every weapon in your immune arsenal, and quality circadian lighting maximizes sleep quality, giving occupants the greatest chance to fight off infection.

Lighting has the capacity to enrich lives and improve health. It’s simpler than you may think to employ HCL technologies that can improve mood, alertness, and productivity during the day and quality of sleep at night.

circadian rhythm