So, my sleep cycle was about like what yours sounds like, I'd often slip back half an hour from one day to the next... But rarely if ever had a sleep cycle under 24 hours. Tried out f.lux a month back, and... Well I'm still on a strange sleep cycle, but a different one. lol. Slept from 8pm yesterday to 3am today, snoozed until 4am. Often I've slept a bit less than normal, but starting far earlier, and waking up early. Maybe that's just a result of only using it for a month, so far.
Probably helps too that I have beige walls and a small desk lamp beside me. Using the desk lamp instead of the full room light / a completely black room helps limit eyestrain.
I have a cheap lamp pointed at the wall behind my monitors that helps immensely with the eyestrain[1]. I like f.lux, but when my schedule gets into full-on night mode, I end up turning it off - especially when working with video[2] or graphics - and forgetting to turn it on it by the time I get back to something more "normal".
1: blinking is a big deal, and I tend not to blink much when tired but focused. Eye drops help.
2: spent a few years working with a company where video is everything.
Probably helps too that I have beige walls and a small desk lamp beside me. Using the desk lamp instead of the full room light / a completely black room helps limit eyestrain.