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Circadian lighting: a comprehensive guide for design professionals

Circadian lighting schemes are central to the design of healthy spaces in commercial, residential, healthcare, and educational environments.

When specifying lighting schemes, it is important for design professionals to incorporate circadian lighting as standard into a project, such is its positive impact on wellbeing.

A circadian lighting system is designed to send light signals to the brain that replicate the signals from natural daylight to keep us active, and to produce melatonin at night time to help us sleep well.

Here at Detail Lighting, our lighting designers and technicians collaborate closely with interior designers and architects to deliver circadian lighting schemes for a range of projects.

What are circadian rhythms?

Circadian lighting schemes support the biological circadian rhythms that regulate our 24 hour body clock.

Our circadian rhythm keeps us healthy by regulating our 24 hour cycle of sleep, rest, hunger, awake time, body temperature, preparedness and more. It synchronises our body cells, each of which has its own clock.

If our cells aren’t synchronised we experience difficulties with sleep, alertness, cognitive functions and more.

The influence of lighting on the circadian rhythm

Light, whether it is natural or artificial, has a huge influence on our circadian rhythm, particularly on our sleep patterns. There is a growing school of thought that when our circadian rhythms are desynchronised, our health can be severely impacted, potentially leading to cases of diabetes, cancer, heart attacks and obesity.

During the day some of us are only exposed to artificial lighting, in the likes of workplaces, classrooms, or in our homes. The lighting is often of poor quality and unable to provide the daytime circadian light signals we would get from natural light.

Continuous exposure to this quality of light affects mood, concentration, and sleep.

In the evenings, in our thirst for entertainment and information, we now remain more active than ever before, often into the early hours using the same lighting conditions we were exposed to during the day.  

Artificial light can therefore disrupt our 24 hour circadian rhythm, usually due to excessive or poorly timed exposure to a variety of conflicting artificial light sources.

If we were only exposed to natural light, our circadian rhythm would be easily synchronised with day and night. Lighting design professionals are therefore tasked with designing lighting schemes that are more intuitive and focused on wellbeing.

Circadian lighting designs complement the natural lighting cycle by moderating and tuning the intensity and colour temperature of electric light to create a healthier environment. A circadian lighting system helps people to experience a normal sleep pattern which is instrumental in supporting physical and mental wellbeing.

The influence of lighting on the circadian rhythm

How does circadian lighting work?

A circadian lighting scheme is designed to communicate with our body clock (also known as the circadian pacemaker).

It tells us when it is daytime and when it is nighttime. The body knows how it should function during different times of day to maximise wellbeing. Circadian lighting sends messages that tell the body to wind down and sleep at night, and be alert and energised during the day.

Lighting design principles for circadian lighting schemes

A well designed circadian lighting scheme supports circadian rhythms. When designing circadian lighting concepts, designers should deliver a strong daytime light signal during the day and a reduced light signal at night.

Lighting design principles for circadian lighting schemes

In a report for the Global Wellness Summit, Dr Stephen Lockley, associate professor of medicine at Harvard, said, “ Given that most of our body systems express circadian rhythms, ensuring proper alignment of our internal circadian clocks, starting with the management of lighting, will have major impacts on human health.”

Through colour tuning, changing the intensity of light and stimulus tuning (of blue light wavelengths to limit the suppression of melatonin), a lighting scheme can positively influence our circadian rhythms.

Two key principles for interior designers and architects who are working on circadian lighting projects, include designing the right colour temperature and also maximising lighting controls.

The colour light spectrum

The colour light spectrum used within lighting design principles for circadian lighting schemes represents an artificial sunrise to sunset.

It starts with a warm orange colour spectrum of around 2700K at sunrise, then upwards to a cooler, brighter blue spectrum light during daylight hours of around 6000K and back again to a warmer spectrum at sunset.

The warmer orange spectrum helps the body to gear up or wind down at the start or end of the day, while the intense blue spectrum light helps the body to be more alert during daytime hours.

Having said that, warmer lighting in commercial or hospitality settings is recommended as it provides a more comfortable environment for customers, where their food will be more appealing and they will feel relaxed with a warmly lit environment.

In modern residential properties, we recommend the colour of lighting should not be higher than 4000K unless the aim is to emphasise the crispness of the architecture or interior.

Circadian lighting systems and controls

Controls within a circadian lighting system are used to optimise its effect on wellbeing.

Colour tuning and dimmer systems allow for the intensity and colour of light to be adjusted. This can be pre-programmed or managed by users to maximise natural light, perform different tasks, accommodate the number of people in a room or respond to the time of day.

By harvesting natural daylight and using controls to adapt artificial light, circadian rhythms can be reset.

LED lighting fixtures for circadian lighting systems

Many products from our range of architectural lighting offers you the ability to produce a different colour temperature, and therefore suitable for a circadian lighting scheme.

For example, the Corona Pro Trimless is one of our most popular downlight options where you can specific it in colour temperatures including 2400K (as a special order), 2700K, 3000K, 4000K and a dim to warm version also available.

The colour temperature has a minimum CRI 92, which refers to the colour rendering index. The CRI measures the ability of a light source to accurately reproduce the colours of the object it is illuminating. Generally, CRI values that are 90 and above offer an excellent representation for a light source.

Contact Detail Lighting to discuss your circadian lighting project

Get in touch with the Detail Lighting team for more information on the fascinating subject of circadian lighting.