Earlier quoted context omitted.
You could just stop staring at your iPhone before you fall asleep?
I don't use my phone in bed. But usually in the hour before bed I'll have to schedule something on the calendar, or set my alarm, etc. Now, I could do one of the following: 1. Reorder my life so that I never look at my phone after sundown. 2. Jailbreak I tried not using my phone for 1 hours before bed, still had insomnia. There's no trivial lifestyle fix that would address the issue f.lux solves.
F.lux also shouldn't be relied upon by itself. How well it works is dependent on the particular frequencies emitted by the RGB components of your screen. I have a 470nm band pass filter that I look at light emitters through, and f.lux reduces such emitters, but doesn't stop them completely. I have constructed a removable orange filter as a supplement.