Cognitive Fitness Chapter 12 – Workplace Lighting – Is it dim in here?

Our latest research looks at the factors that most impact our cognitive performance – so individuals and organisations can understand and adopt best practices to get everyone’s brain in peak condition. Recent blogs have considered environmental factors as we build up a picture of what goes on in the office. Our previous blog explored what effects multitasking has on mental performance. This time we consider the effect of lighting…

Light is a basic need for humans. It affects us physically, physiologically and psychologically. Recent studies have shown that insufficient or inappropriate light exposure can disrupt standard human rhythms which may result in adverse consequences for cognitive performance, safety, and health.

How does light impact the human brain?

We capture light information exclusively by the eyes using photoreceptors (rods and cones that detect visual information). In fact, our eyes are only sensors that detect colour and light variations and reflections. It is in fact our brains that translate this data into, what we would all understand as ‘images’. So our eyes don’t actually ‘see’, they only ‘sense’. It’s our brains that ‘see’.

Studies on animals and humans have shown that light stimulates a wide range of physiological responses like resetting the timing of the circadian pacemaker (your biological clock), and improving alertness.

Circadian rhythms are kept in sync by a variety of cues, including light. High frequency and intensity lighting promotes alertness. Without this stimulus, the body can think it’s time to conserve energy and rest.

What light do we need?

A well-known study carried out in an office environment in 1993 measured the brainwave patterns (EEGs) of research subjects, whose delta waves (an indicator of sleepiness) were reduced when lighting levels were lower (450 lux – roughly equivalent to a bright office) as opposed to bright (1700 lux which would more normally be used for very detailed work). The conclusion was that bright light has an alerting influence on the central nervous system (Kuller & Wetterberg, 1993). For comparison, the level on a clear day outside is 10,000 lux and ambient light levels of around 300 lux are felt suitable for most office tasks (with higher levels provided through task lighting where additional detail is needed).

It has also been shown that blue light (in this case wavelength 460 nm) is helpful for increasing alertness and accuracy, when compared to “normal” light. Advanced lighting (LED) technologies have also been shown to promote increased alertness and visual cognitive efficiency among workers when compared to more traditional alternatives (Hawes 2012).

Brightness levels contribute to our perception of spaciousness and the degree to which they look appealing.

Is all light good?

While light, and exposure to natural light is known to be essential to our physical and emotional wellbeing (according to medical experts and researchers), excessive brightness (i.e. glare) can be problematic. When there are uneven levels of brightness, this can cause tired eyes and be uncomfortable. The issue is that there is less contrast for the retina to detect, which causes strain. Glare can be present in many parts of the office, depending upon the direction of the sun and the amount of solar “management” within the building design.

Another contributor is the glare that can be generated by glossy workstations in the office. The trick here is to ensure the workstations are positioned such that the light doesn’t bounce up into the user’s eyes – we need sufficient light but minimum glare.

So what can you do to improve cognitive performance?

Many offices and their workplace design concentrate on dedicating all the natural light to the open plan parts of their offices, so that the majority of occupants benefit from this condition (as opposed to lining the floors with offices or meeting rooms around the perimeter – thus depriving the rest of the office of the much-appreciated natural light). There is evidence that daylight keeps us more alert and accurate, whereas artificial light increases our levels of fatigue and sleepiness. Furthermore, it would be wise to ensure the workplace experience consists of both natural and artificial lighting.

This is linked to the production of cortisol (stress hormone) which is produced in lower quantities the more time you spend in artificial light. Cortisol helps us handle stressful situations and impact mental clarity and performance. The other important mechanism is the production of melatonin (the substance that causes you to sleep or wake) which increases when there is little or no natural light and falls when it is time to wake up. If you then work in artificial light all day, there are signals to increase melatonin production, leading to drowsiness.

That said, there is still tremendous variability in terms of how much light penetrates into the office space – and indeed depending upon the angle of the sun during the day, many people find they have to deploy blinds because the sunlight is just too strong.

People’s ability to move around to find the right lighting conditions will depend upon how mobile their role and technology allow them to be. Given that lighting is important, particularly for tasks requiring a lot of focus and concentration – try to be aware of the lighting and think about it (along with temperature and noise) in seeking out the conditions that you need, and choose locations where you feel you have sufficient light for the task, without it being overly bright or dazzling from glare or too dim to focus on the task you’re working on.


Here are some thoughts:

  1. Find an area with high levels of light if you want to work on tasks that require high levels of concentration
  2. Adopt an agile working approach that lets you work in different places with different lighting conditions (intensity and colour). This will ensure you are provided with different moods and stimulation during the day
  3. Be aware of your surroundings – you may instinctively know that some places in the office are more comfortable for you than others…but you may not have realised why
  4. Try to choose places to work that are appropriate to the task that you are undertaking – we don’t always need very bright conditions and more subdued lighting can be conducive to more relaxed activities
  5. Bear in mind that light levels are key to our sleep patterns and light exposure in the early morning or late at night will shift our circadian rhythms


Give your brain a great day – be light aware!

Next time we’ll look at the 11th factor that came out of the research – cognitive stimulation.