Category Archives: sleep

Light and Sleep

knowledge, news, sleep, ,

There was an interesting article in The Guardian today about a new blood test that can detect whether someone is sleep deprived. The idea is to use it to prosecute drivers involved in accidents who have had less than 5 hours sleep. According to the article driving after less than 5 hours sleep is as dangerous as driving after drinking alcohol. Experts are divided on the ethics of this.

This was particularly interesting for me for two reasons. Firstly, because this time last week I was on a flight from Manchester to LHR, en route to Texas where I took part in a couple of panel discussions about colour psychology having gone to sleep at 11:30pm the night before and left the house at 3:30am after fitful sleep for less than four hours. During the 1.5 hour drive from Leeds to Manchester in the early hours I had felt completely awake; however, I wonder whether I would be able to make this journey in a few years if the legislation is introduced.

But secondly, because my own research is concerned with the effect of light sleep and the devastating effects that lack of sleep can have on our health and wellbeing. A discussion about this topic actually came up during the Texas trip. I would encourage everyone to listen to Matt Walker’s superb TED talk – Sleep is your super power. We now know that light plays a crucial role in maintaining a healthy sleep schedule. Healthy sleep is entrained by exposure to bright light in the few hours after waking and to lack of exposure to light in the hours before going to bed. There is debate about the relatively importance of the light being blue. The light-sensitive cells in the retina that are implicated in sending signals to the hypothalamus in the brain (from where the release of hormones is controlled) are maximally sensitive to light at about 480nm but there is some evidence that longer wavelengths of light could also influence alertness (in other words, the cones may also be involved). Here is one of my own papers on this topic:

Lin J & Westland, 2020. Effect of long-wavelength light on electroencephalogram and subjective alertness, Lighting Research and Technology, 52 (6), 763-774.

There is already growing research into the use of light and light-related products to help us to sleep better. As public awareness of this issue grows it is inevitable that interest in to this topic will increase. Perhaps such products could be used to mitigate the effects of poor sleep in situations such as the one I was in last week.

See my related posts

colour helps you sleep
non-visual effects of light

Texas Design Week

design, opinions/rants, psychology, sleep, , ,

I’m off to Texas on Monday for Texas Design Week. I will be taking part in two panel discussions – one in Dallas and one in Houston – invited by Harlequin (part of the Sanderson Design Group) with whom I have been collaborating for a colour of years now. Last year I did something similar in Atlanta for Atlanta Design Week so I know what to expect. And we have done have half a dozen or more such panels in the UK over the last 24 months. I will be sharing the platform with designers of course and my role is to bring some findings from the world of colour science to the table. The mix of science and design in the discussions is always a lot of fun.

My relationship with Harlequin started when I was asked to write a white paper about colour and its effect on people at home and in the workplace. You can download that white paper here if you are interested.

Talking about colour in our lighting lab

In the white paper Soojin Lee and I identified two different ways in which colour (and light) can affect us. We referred to them as emotional and physical.

The emotional effect is often caused by associations; we associate certain colours with certain ideas or memories. We might find a blue room relaxing, for example. There is some commonality between people (because we all live in the same world) but at the same time there are differences between individuals. This is the same reason why, for example, blue is a colour liked by lots of people, but that we can find individuals who don’t like blue. I am one of those.

The physical effect is more to do with the direct effect of colour and light on our physiology. For example, we need exposure to lots of light in the morning and we need to avoid such exposure at night, to keep our circadian system in a healthy state and to enjoy good quality sleep. There is evidence that blue light, in particular, is alerting and can keep us awake. Because we all have the same physiology there tend to be fewer individual differences in these effects.

Sometimes these two effects are contradictory and can even occur at the same time. It’s why a blue bedroom (blue-painted wall, blue curtains or blue bed linen) can be relaxing whilst at the same time exposure exposure to bright blue light can be alerting.

So is blue alerting or relaxing? It depends. It doesn’t actually make any sense to ask the question in that abstract way. We should ask whether blue lighting or blue paint, for example, is relaxing – and then we can have a meaningful response.