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Lights and Mood

understanding you chronotype for better sleep blog

As the days get shorter, I’ve had lots of conversations about SAD lamps – are they just a gimmick?

Well yes and no – there is no substitute for going outside – the vast majority of artificial light sources just don’t have the edges of the visible spectrum that sunlight delivers – the near violet that plays a role in metabolism and synthesising vitamin D for example, This 2013 paper from Dermato-Endocrinology gives a good overview –

​ Article: Sunlight and Vitamin D- A global perspective for health

If you, like me, you were always told to cover up to avoid skin damage from exposure to sunlight, it seems that it may be a bit more complicated – some cancers seem to be inhibited by sunlight.And living in a low-sunlight country seems to be a contributing factor. This recent paper from a team in Brazil explains some of the mechanisms involved.

Article: The Role of Vitamin D and Sunlight Incidence in Cancer

And just to complicate things a bit more, your chronotype seems to make a big difference to your response to those narrow bandwidth wavelengths present in sunlight – and not in most artificial lighting – this paper from Chronobiology International is an interesting read –

Article: Narrow-band ultraviolet B (NB UV-B) exposures improve mood in healthy individuals differently depending on chronotype

It’s tempting to think you should just throw blue light at everything, especially when you’re working – or at least trying to. But this experiment – admittedly small-scale and, as usual, on a population of healthy academics – but their findings suggest that it’s worth considering the colour temperature too

​ Article: Effect of Light Color Temperature on Human Concentration and Creativity

Back to the chronotype question – it may make a bigger difference than we thought to how you and the kids survive the winter.


Chronotype, somnotype and trototype as the predictors of the time course of subjective and objective indexes of sleepiness in sleep deprived subjects,

Chronotype and Childhood Psychiatric Disorders

Eveningness increases risks for depressive and anxiety symptoms and hospital treatments mediated by insufficient sleep in a population‐based study of 18,039 adults

Your chronotype for your self

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