I have had success with an extremely aggressive red filter. My unchecked sleep schedule has me going to bed around 4 am, consistent over decades. I don't consume caffeine or any other stimulant. In the last 4 months I switched my lights to LED bulbs to turn red at 6pm and use QRedshift on Linux (Mint) with the temperature set to 1000k at 6pm. I have consistently been falling asleep around midnight. What is remarkable to me is that I am actually feeling tired at night.