Circadian rhythm: Seeing the light of day


A deeper understanding of how lighting affects our circadian rhythm has given rise to the introduction of bio-adaptive lighting: products that replicate the variations in colour and intensity of light found in the natural world. Paul Skelton explains.

Despite being around for more than 100 years, artificial light is still relatively ‘new’ when you consider humankind’s evolutionary process. Conceivably the single most important invention of all time, second perhaps only to plumbing, electric light has fundamentally altered the way we interact with the world around us. But as time and technology march on, so too does our understanding of how artificial light affects us at a biological level.

As a result, a number of commercial lighting suppliers are introducing bio-adaptive, or ‘human centric’, lighting solutions to market. Built to support a person’s circadian rhythm – the 24-hour period that tells our bodies when to sleep, wake and eat – these systems use clever technology to replicate the natural pattern of the sun as close to reality as possible.

“It is now possible to use the principles of bio-adaptive lighting easily and cost-effectively in the workplace, at home and especially in sensitive environments such as schools and health care,” says amBX chief operating officer Neil MacDonald.

“It’s not just about feeling better either; the right type and level of lighting can dramatically improve our performance of tasks and increase productivity. The bio-adaptive lighting technology that is now being seen in the marketplace provides the means for everyone to realise these benefits.”

According to Rene Rieck, the automation manager for electronics manufacturer WAGO, lighting designers are increasingly specifying bio-adaptive, or ‘melanopic’, lighting. As a result, WAGO has developed a program for its control system whereby users can run a complete 24-hour daylight cycle using their lights.

“The word ‘circadian’, as in circadian rhythm, comes from the Latin ‘Circa Diem’, which means ‘about a day’. This is why WAGO has enabled its control system to mimic sunlight patterns over the course of a day. We’re replicating the light patterns found in nature,” Rene says.

“When activated, our daily cycle scenario activates the lights in a building at 3,000K. Over the period of one day, the lights will increase to 6,500K and then slowly return to 3,000K.

“Over generations, our bodies have adapted to sunlight, which is why we get tired at night and wakeup in the morning. But these days a lot of people are awake at night and sleep during the day – their biorhythms are upside down.

“In the same way a leaf opens in the morning and closes in the evening, humans also work to a 24-hour wake/sleep schedule. If light is missing, a person’s inner clock will go out of sync: fatigue, lack of drive and in the worst case, depression can result.”

The principle of bio-adaptive lighting is to provide artificial light that is controlled to match the needs of human biological cycles, or circadian rhythms, in the most effective and appropriate way. It provides for improved health and wellbeing and supports aspects of human behaviour that benefit from varied and changeable lighting.

“We are all governed to some degree by the circadian cycle. Light is the most powerful synchroniser of the human circadian clock and the timing of light exposure during the course of a day is responsible for how circadian rhythms are synchronised with the environment,” Neil says.

“Perhaps the most important consideration for lighting in the workplace is the use of natural daylight; however, many work environments rely on artificial light either wholly or partially. Here, the lighting should ideally be capable of delivering varying levels of illuminance and colour (especially ranges of cool to warm whites) and be subject to control systems capable of delivering bio-adaptive effects. In particular, workers should be given control over their own individual lighting as far as practically possible.”

Lighting can energise working environments through increased illuminance. Changes in colour temperature, when delivered at the right time of day, can have a powerful impact on worker wellbeing and productivity. And now, control systems such as amBX and WAGO are capable of delivering bio-adaptive lighting effects, as well as multi-faceted controls, in standard office configurations.

At home, in addition to simple settings for comfort, reading etc., lighting can be used in many ways to deliver the benefits of bio-adaptive lighting. Products such as Philips Hue and Photonstar Halcyon are good examples of controllable, colour-changing lighting that is available today.

“There is a rising need for lighting to support medical conditions and there are emerging solutions which offer sophisticated control capabilities which can support recommended treatment with light in the home,” Neil says.

Colour plays an important part too. One study from the Light Research Program at Thomas Jefferson University in Philadelphia found that blue light strengthens and stimulates connections between areas of your brain that process emotion and language. This means that blue light may, in turn, help people to better handle emotional challenges and regulate mood over time.

“Blue light is prevalent in sunlight, so your body absorbs the most during the summer and much less in the winter. Because of this, the researchers suggested that adding blue light to indoor atmospheres, as opposed to the standard yellow lights typically used, may help boost mood and productivity year-round, and especially during the winter.

“This doesn’t necessarily mean that we should all now have lots of different coloured lighting since blue is often in white light. But having the ability to vary the colour of white light, or the colour temperature as it is known, is a critical factor in effective bio-adaptive lighting. Introducing colour changes and even tints at certain times of the day is a highly effective way to deliver good bio-adaptive lighting.”

Throughout the evolutionary process, human beings have been exposed to artificial light for an extremely short amount of time. However, many of us now spend most of our time under artificial light and until very recently this has failed to reproduce the light experience for which we are ‘programmed’.

“Studies have shown that light affects sleep habits, depression and mental functions,” American Lighting Association director of engineering and technology Terry McGowan, FIES, LC, says.

“The term ‘healthy lighting’ has been used to indicate that light can act like a drug where the strength, timing and type of light can be used to alleviate problems and enhance well-being. The ‘prescription’ is simple: people need bright days and dark nights that match the natural day/night circadian cycle.”

Something else worth keeping in mind is as people age, it becomes harder for them to adapt to changes in the amount of light to which they’re exposed.

“Older people’s sleep and wake cycles are harder to maintain if they are not exposed to daylight early in the day and sleep in a dark room at night.

“Even the colour of the light is important. The human circadian system is more sensitive to the blue portion of the spectrum than other colours, so it may be beneficial to limit the blue content of lights used for illumination during the evening,” Terry says.

Blue light will suppress melatonin in your system and make you more alert. So it’s best to use warmer-coloured light in the evening.

The colour of light is key to effective bio-adaptive lighting. In a study into lighting and clinical depression people who were exposed to bright blue light for an hour each morning for just three weeks experienced more improvements in their depressive symptoms than the control group, which was exposed to red light. They also had increased levels of melatonin in the evening, which helps with sleep and regulating the internal body clock, and lower levels of the stress hormone cortisol. Further, the improvements felt by the light-therapy group were comparable to those experienced by using antidepressant drugs.

In another study, exposure to blue LED was shown to affect sleep quality and median body-temperature peak in Alzheimer’s disease patients. Median body-temperature peak was delayed by approximately two hours after exposure to blue LEDs, compared with exposure to red LEDs, and sleep quality was improved. This pilot study demonstrated that light, especially LED lights, can be an important contribution to helping such patients regulate their circadian functions.

“The original timers for the circadian rhythm are nature and natural daylight. Daylight changes in intensity throughout the day – in the morning and evening twilight with low illuminances the colour temperature varies. A biologically effective lighting system mimics these variances and supports the circadian rhythm of the human being with different illuminances and dynamically changing light colours: stimulating morning mood, bright light for concentration phases or gentle transfer into the evening,” Rene says.

In an office environment, lighting systems with preset, automatically running lighting moods can also help to strengthen the wellbeing and concentration of the employees.

The biological effect of light is mediated by the eye but according to Rene, works independently of the visual process. In addition to the requirements for the general quality criteria and the energy efficiency of an illumination system, the criteria of the biological effect of light must also be met. Important factors following nature’s example are: illuminance (vertical to the eye), lightness, light direction, light colour, dynamics, time of day, and duration of biologically effective light exposure.

“The biological effect of light increases with the visible area of ​​the light source. Illumination concepts that include wall and ceiling surfaces are therefore particularly efficient. Thus, the light reaches the eyes from above and from the front. For example, flat luminaires that can be combined into light ceilings or pendulum lights that radiate a portion of the light indirectly against the ceiling and to the upper third of the walls are well suited. Wallwashers can also be integrated effectively into the lighting concept.”

“We’ve also introduced a ‘light shower’ feature whereby you receive a short burst of 6,000K light. This means if you have a meeting, for example, and want people to pay attention you can use your lighting to make them more alert,” Rene says.

“Finding ways to increase motivation and concentration among office workers will be a significant trend in commercial lighting in 2017 and beyond.”

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Reference: Connected Home