Having just returned from a few days in the sun for a dermatology conference, one cannot deny the benefits of sun exposure, especially when one lives somewhere where drizzle is the norm.
We all know that the reason we have blue skies is because the sun’s rays scatter in the Earth’s atmosphere. Because blue light has shorter and smaller waves, it gets more scattered than the other colours and hence why we see the blue colour more.
And apart from dermatologists always harping on about UV rays and skin damage, blue light devices have been around for some time and occasionally used for their therapeutic benefits in psoriasis and acne for example. With the pandemic and the massive rise in screen use from laptops, mobile phones and television screens, there came a worry that the blue light from these devices could not only alter circadian rhythms but also promote skin hyperpigmentation and photoageing.
Is there any truth in this?
Well, the April edition of Clinical and Experimental Dermatology did contain a review article on blue light and its effect on the skin.
[Das A, Sil A, Kumar P et al. Blue light and skin: what is the intriguing link? Clin Exp Dermatol 2023. doi 10.1093/ced/llad150. Online ahead of print.]
This is a review article, looking at all literature published on Pubmed, Medline or Embase with the words ‘blue light’, ‘acne vulgaris’, ‘psoriasis’, ‘eczema’ or ‘infectious diseases’.
What did they find?
There have been several studies which have showed improvements in acne, atopic eczema and psoriasis with blue light therapy. The improvement depended on the intensity of irradiation, duration of treatment and a property of the light called the fluence with a higher fluence, intensity and duration of treatment giving the best improvement.
With regards photoageing, pigmentation and melasma there is definite evidence that blue light can induce signs of photoaging in the skin and skin pigmentation but not so much for melasma.
How does it do that?
Blue light is part of the visible light spectrum and we know it has the shortest wavelength. It also has the highest energy and so can penetrate deep into the skin layers. There it can damage cellular DNA, induce reactive oxygen species, induce enzymes that break down collagen and impair wound healing all of which can promote photoaging.
From the pigmentation point of view, it is thought to interact with proteins in the skin that promote melanin production.
The study looking at melasma looked at computer screen use and its effect on existing melasma lesions and fortunately didn’t find any worsening of these lesions.
So what is the advice?
From a photoageing and pigmentation point of view, the advice would still be to use sunscreens and ideally ones that contain zinc and titanium dioxide as they have been found to be effective against blue light induced UV damage. Methylene bis-benzotriazolyl tetramethylbutylphenol (get your tongue around that!) is another UV filter that has been shown to be protective against blue light.
What about blue light devices to treat acne, psoriasis and eczema?
Several years ago, Philips produced a blue light device that could be strapped on to limbs to treat psoriasis plaques but this is no longer available in the UK.
Other than that, standardised, large, randomised controlled trials looking at various blue light devices that are available for in-home use are required to improve guidance on how to recommend or use them.
Kind regards,
Sandy
Dr Sandy Flann, Consultant Dermatologist
