From Annemieke Wigmore
Colour-tunable LED bulbs are good news not just for insomniacs keen to influence circadian cycles, but also, for those of us who have, or will develop, macular degeneration (17 November, p 24). Causes of this eye condition are thought to include too much light in the blue wavelength.
Increasingly, incandescent bulbs are being replaced by more energy-efficient halogen, LED and metal-halide bulbs, all of which emit more blue light.
Cudworth, Somerset, UK
