Why Blue Light Matters, and How Blue-Light-Blocking Glasses Can Help Nearly a third of us are constantly online (and that number shoots up to almost half of us in the 18- to 29-year-old range).

If you’re looking for a solid, blue light blocking lens — one that filters out most of the harmful colors on the blue end of the spectrum and 100% of UV rays — look no further than Warby Parker.

He conducted two studies on the effectiveness of blue light-blocking glasses on digital eye strain, and he joins us now. Welcome to the program. MARK ROSENFIELD: Thank you.

Blue-light-blocking glasses promise to filter out the brain-stimulating blue rays emitting from your laptop, phone or TV screen — thereby reducing headaches, dry eyes and fatigue.

Glasses that claim to shield your eyes from screens’ blue light and supposedly help you get better shut-eye may not provide much benefit at all — other than elevating your accessories.

Blue light from computer screens and smartphones stimulates eyes and can cause sleep problems — but a new analysis finds blue light blocking glasses may not be much help.

Learn about how light is transmitted through different materials and how to create ray diagrams to show light transmission with this guide for KS3 physics students aged 11-14 from BBC Bitesize.