Blue Light. What's the big deal?

I had a great conversation with a sleep consultant the other week about the colour theory concept behind Minimello and how that sits with the advice she gives parents of children with sleep issues.
I wanted to know whether colour came up in her conversations and whether the guidance she gives aligned with what I had learnt about colour, for example blue colours having calming properties, greens use less energy for the eye to process, while reds and bright pinks are stimulating and can energise children at bedtime.
So I was interested to hear from her that blue light which comes mainly from screens is not good due to its impact on production of melatonin, required for good sleep. Whereas warm colours, in particular red are deemed better for sleep.
So who was right? Were we both right in different ways?
I really wanted to understand it myself so set about yet more research which led me to a professor of colour from Leeds University who kindly explained that we were both right actually.
Apparently, since around the year 2000, scientists have been aware of the impact of screens on melatonin levels, which produced by the body between roughly 8pm-midnight. Most screens are set with a bright white, bluish toned light, hence the negative association with the colour blue at bedtime. However many children’s night lights are also coloured blue, the Calpol plug in for example, and the Gro-clock are both blue tinted. So why would that be? Well, it turns out that the light brightness of a night-light or room decor is not sufficient to affect melatonin production, whereas the light from a screen - phone, tablet or television is, and should be turned off one hour before bedtime. So the blue of the light is being used for its calming qualities, as I had thought was the case from my research.
So in short - dim blue night-lights and blue decor are calming and don’t impact melatonin production, whereas bright, intense screens, which emit a blue/white light should be limited to no less than 1 hour before bedtime.
Red and warmer coloured lamps and decor are likely to have a stimulating effect because of the effect these colours have on the brain but bright lights with warmer tones have less impact on melatonin levels.
- Joanna Dunn