- Lighting Solutions
Our sensitivity to light can vary according to age1, gender2, and genotype3, and our inter-individual difference in light sensitivity is estimated to be over 50 fold4. Regardless, light exposure has been shown to have a big impact on many people’s physiology and mood. It can also impact our alertness, safety and productivity in the workplace, and at home.
There is a large body of literature demonstrating the role of circadian rhythms and sleep in health conditions, and that enhancing these processes via optimal light exposure may have huge positive implications.
Here are some starting considerations for achieving lighting for wellbeing:
The effect that light has on our body clocks depends on the timing of exposure5. Light delivered in the evening can delay the timing of our circadian rhythms, leading us to feel awake and tired later on subsequent days. Conversely, light delivered in the morning can advance our rhythms, resulting in us feeling awake and tired earlier on subsequent days.
Intensity and colour spectrum
As well as the time at which light is delivered, the degree of impact that light has on the human body depends on its spectral quality (colour), the intensity (brightness) of the light stimuli, and the duration of exposure. For the average person, light as low as ~30 lux can have a profound impact on some non-visual light responses. And blue-enriched light suppresses the release of melatonin, delivering alertness-promoting effects.
In the workplace, blue-enriched light can increase subjective alertness (and quality of subsequent sleep), concentration and performance. It can also enhance positive mood and reduce fatigue6. Such light at night, however, can delay our circadian timing, making it difficult to sleep until later at night. Compounding this effect is that blue light suppresses the sleep-promoting hormone melatonin in humans, which will further affect our ability to fall asleep, and achieve deep sleep. Having this knowledge allows us to adapt our lighting according to our desired timing.
The effect that light has on the circadian system depends on the brightness (intensity), with brighter light eliciting a greater physiological response4. Additionally, the circadian system is most responsive to short wavelength (~480nm) blue light7.
1 Crowley, Cain, Burns, Acebo, & Carskadon, 2015
2 Monteleone, Esposito, Rocca, & Maj, 1995
3 Roecklein et al., 2013
4 Phillips et al., 2019
5 St Hilaire et al., 2012
6 Mills, Tomkins, & Schlangen, 2007; Viola, James, Schlangen, & Dijk, 2008
7 Bailes & Lucas, 2013