Flux definitely helps me, but it is always better to just read a book an hour before bed :)

Same. It helps but there's no replacement for no screen time before bed.

But...so...hard..!

Use F.lux any time > 7PM-ish. But still make sure you turn off any screens 1-2hrs before bed. It makes a huge difference.

If you spend a significant amount of time in front of a screen you should try to reduce blue light at all times just to reduce eye strain. flux is great but just a simple orange background / window theme will go a long way. This isn't a replacement for putting down your device an hour before you go to bed. Even if the light is orange / yellow you're still shining it in your eyes.