Lighting at work is one of the most common sources of discontent amongst employees when it comes to the working environment, and for good reason. The poor-quality artificial lighting found in many workplaces today can contribute to several damaging side effects – headaches, eyestrain, low productivity and depression, to name a few. For some workers, particularly those on night shifts, these effects can be even more severe.
Despite it being clear that the health impact is real, it is less clear what ‘good’ lighting looks like. What qualities should we actually be looking for in lighting? We know that sunlight is good for our health and wellbeing, so is it possible to replicate its spectral composition?
What is Colour Rendering Index?
Thankfully, this is where the Colour Rendering Index – or CRI – comes in. The Colour Rendering Index of a light source is a way of quantifying its similarity to natural light. It measures the colour spectrum of light produced by a given source and, therefore, how accurately it shows true colour.
The index runs from zero to 100, with higher numbers denoting a better ability to render colours – though no artificial light source will have a perfect 100 CRI. LED lighting is now available that possesses a CRI of 95+, which is as close to natural sunlight as it is possible to get. To put it in context, industry standard LED lighting typically produces light with a CRI in the low 80s, while fluorescent lighting is considerably lower.
What does this mean for employees?
Installing light with high CRI values could bring about considerable improvements in the health, wellbeing and productivity of staff, even helping to replicate sunlight in deprived spaces. Not only can this alleviate many of the health effects caused by lower levels of visibility, such as eye problems and headaches, it can also impact mood, energy and alertness levels.
Serotonin, the chemical produced in the brain that contributes to feelings of wellbeing, is released through exposure to sunlight that passes through the eye. High-CRI lighting that is able to mimic natural light can therefore stimulate the brain to produce more serotonin. This could significantly help any employees that suffer from types of depression such as Seasonal Affective Disorder.
Some high-CRI lighting technologies are also configured to mimic the behaviour of the sun through changes in light colour and intensity throughout the day. This entrains the body’s natural circadian rhythm – or ‘body clock’ – to the behaviour of sunlight, helping employees to fight fatigue, boost energy levels, and potentially improve sleep patterns.
Can lighting help shift staff?
For night shift workers, the effects of high-CRI lighting could be even more transformative. Research links night work to obesity, diabetes, insomnia, and certain types of cancer and cardiovascular diseases. Our physiological programming through the circadian clock – synchronised to a 24-hour day and reliant on regular exposure to light and darkness – is integral to much of this.
When workers are regularly sleeping during sunlight hours, then working at night, the quality of indoor light becomes all the more important, as the circadian clock essentially needs to be reversed to enable normal biological processes. In addition to serotonin, melatonin – the chemical that tells us when it’s time to sleep – is linked to light. Suppressing melatonin by keeping the body awake when it should be resting is associated with an increased risk of serious diseases.
To promote health and wellbeing in night shift workers, we therefore need to create lighting that can help the body retrain its clock to ensure serotonin and melatonin can be released at the right times. Lighting with a CRI of 95+ is able to trick the mind into thinking it is natural light, thereby simulating a fake ‘daytime’.
Lighting with a high CRI can also help night shift workers feel more focused and alert, alleviating any groggy symptoms from artificial lighting. Sharpened concentration levels could potentially help to reduce the number of accidents and injuries that occur on night shifts – significantly higher than the day shift counterpart – and lower absenteeism rates, which are over double the day shift figures.
What does this mean for the bottom line?
Businesses that invest in lighting that’s good for staff health and wellbeing can therefore help counteract what is known as the ‘night shift tax’, where injuries, absences, and low productivity ultimately affect the company’s bottom line. High CRI, LED lighting is also more accessible to the market than ever and can often be installed at no upfront cost, with payback made from generated energy savings.
Workplace lighting shouldn’t centre on light level intensity or the number of light fixtures in a given space; it’s about the quality of that light and its ability to render colours. High-CRI lighting that can mimic sunlight will not only make employees feel like they are working in a more naturally-lit environment, it will have a much deeper, biological impact. By supporting the body’s natural circadian rhythm, or helping us settle into a new one, it can enable humans to function to the best of their ability – ultimately leading to a happier, healthier workforce.