Blue light and sleep: separating signal from noise

Blue wavelength light (~480 nm) suppresses melatonin more than other wavelengths — but in real-world brightness, the effect from a phone is small relative to ambient room light.

The bigger issue with screens at night isn't the wavelength: it's the content. Doomscrolling, social media, and exciting TV keep your nervous system aroused, which is what really delays sleep.

Dim screens to the lowest comfortable brightness 60+ minutes before bed. Use night-shift mode. But the bigger win is choosing calmer content: a book, an audiobook, or a podcast beats Twitter every time.