Many phones have OLED screens that are capable of emitting only red light, if a software filter is applied, so there's no need to develop specialized hardware.

Many phones have OLED screens that are capable of emitting only red light, if a software filter is applied, so there's no need to develop specialized hardware. Chances are that the reason blue-light filtering glasses and night-time mode aren't working for you is the same reason that it doesn't work for anyone; studies show that the color temperature of light doesn't affect sleep or circadian rhythm: https://www.bbc.com/future/article/20260407-the-blue-light-from-your-phone-isnt-ruining-your-sleep https://www.bbc.com/future/article/20260407-the-blue-light-f... https://www.manchester.ac.uk/about/news/researchers-discover-when-its-good-to-get-the-blues/ https://www.manchester.ac.uk/about/news/researchers-discover... A red-only filter for your phone would be great for preserving night vision, though. If you want help sleeping, getting lots of light in the morning is greatly beneficial, especially full-spectrum light, including infrared. It's also helpful to avoid alcohol and caffeine, especially so later in the day.