Circadian Lighting

Close up of an eye

Humans have an internal ‘body clock’ that follows the Earth’s natural daily cycle of light and dark. Though we may not be acutely aware of it, our internal systems are hard-wired to synchronize with the daily pattern of day and night. This is a natural and intuitive reality of life on Earth; as almost all living things have a ‘daily routine’ that includes a balance of activity and rest. In the case of us humans our normal daily routine of alertness and sleep is regulated through the release or suppression of melatonin and other hormones. ‘Circadian Rhythm’ is the term used to describe this natural internal biological 24-hour cycle.

This natural cycle is in large part governed by light. It is common knowledge that the human eye perceives visible light through the retina and light sensitive ‘rods and cones’ which give us our vision, but in addition to these visual photo receptors, our eyes also include what are known as non-visual (NV) photoreceptors. These NV receptors play the important role of daily re-setting our circadian clock. They provide a manual reset to our internal circadian cycle and signal important hormonal changes in our bodies. Maintaining these natural cycles is vitally important to our health and wellbeing. These NV receptors are adapted to daylight and are most sensitive to blue light.

In a world where we are now exposed to light at all times of the day and night, our circadian patterns can sometimes get ‘out of sync’. The effects circadian disruption can include a wide range of health effects including sleep disorders, inflammation, obesity and metabolic disorders. Minimizing these negative health impacts should always be the primary focus of circadian lighting applications. The seriousness of these health impacts is why your smartphone or laptop now has a ‘night-shift’ feature which limits blue light from the screen as you approach bedtime. Some efforts have been made to ‘hack’ this biological reaction and encourage increased focus or alertness at desired times through artificial light. These sort of applications are often well intentioned, however, in our opinion the ultimate application of circadian lighting should be to support human health and wellness.

Circadian lighting has many applications for health care, schools, universities, residences, workplaces and indeed all interior spaces where users spend a substantial amount of time under artificial light. The need for circadian lighting is greater in spaces where natural daylight is not accessible either due to limitations of the building design (large buildings with limited windows and skylights) or time of use (i.e night shift). Furthermore, sites in the far north of our country experience much wider variance between day/night cycles throughout the year and circadian lighting designs can assist in helping users sync up with the typical 9-to-5 schedule expectations dictated by lower-latitudes, even when the environmental ques are wildly different.

tree with sunny and stormy background

Circadian lighting applications are sometimes described as human-centric, color-tuning or tunable. Sometimes these systems come equipped with local controls, which allow users to adjust the Correlated Colour temperature (CCT) and blue content of the lights in each area. Determining which fixtures and designs provide enough blue light to activate a circadian response, and how best to control those systems is a technical and design challenge that requires expert involvement.  As there are a range of systems and applications available in the market, working with a reputable lighting design firm should be an important part of any circadian lighting project. If you are interested in learning about how circadian lighting can benefit your organization, reach out to our exceptional design team at Dynamic Energy Services.

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