It was good to see the LightAware charity highlighting the particular problem of blue-rich LEDs in the discussion on the rise in light pollution (Letters, 7 November). I loved Jacqueline Yallop’s rich and vivid article (Everything from our sleep to our hormones relies on the dark. So why are we so intent on destroying it?, 31 October), but felt it missed this important point: it is not just the quantity of light that has changed in recent decades, but the quality of that light.
The rush to transition to LED lighting resulted in a botched job: councils throughout the UK installed light in our public buildings and spaces, and in our streets, that was far too intense and contained too much blue light. This is precisely the wavelength of light that most disrupts the circadian rhythm –not just sleep but almost every other physiological process – in humans and the rest of the natural world.
