More flexible / manual control
I've been using f.lux for a couple of weeks now, and it's great! It's already helping me a lot to get my sleep schedule more consistent.
However, I found that it wasn't easy to set up the way I wanted, because of the rigid timings - dimming at sunset, one hour before sleep bedtime mode, daytime mode set to wakeup time, and in particular, a fixed eight-hour sleep period. It sounds reasonable, but in practice it's been too much of a "one size fits all", which really doesn't fit me - even though I have quite a normal profile.
I want to start with a consistent bedtime target, eg. midnight. One thing I have trouble with is "bedtime procrastination", getting caught up in the Internet or TV, even when I'm tired. Having f.lux go to bedtime mode and start sending the backwards alarm clock notifications is - or would be - really helpful.
That means I have to set wake-up time at 8am. But I rarely sleep eight hours, it's seven if I'm lucky. So my screen is still in bedtime mode when I get up, even though the sun is already up. It also means the times in the notifications are wrong. I've now set wake-up at 7am. So my screen goes to bedtime mode two hours before bedtime, at 10pm. I don't mind that so much I guess, but the alarm notifications get annoying, and I've had to turn that off. Now I'm looking for another app that can do similar notifications - recommendations? I tried Apple Reminders, but it doesn't work well.
The other thing is I tend to get depressed in the winter, and the days are short here. Keeping daylight lights on longer in the winter seems to help. I managed to set my location to a spot closer to the equator (after all, that's where humans mainly evolved) with sunset times that suit me.
So now I've got things working reasonably well - thought still not quite as I'd like. But I feel like I've been fighting against the "smart" interface and jumping through hoops the whole time. It would be so much more straightforward if I could just set my own times manually, eg., daytime mode at 6:30 am, sunset mode at 7:30pm, bedtime mode at 10:30 pm, with notifications starting at 11pm, relative to a midnight sleep time and/or 7am wake time.
Apologies if this has all been said before, I'm sure you're aware of it, but I thought I'd just add my story to the mix. My feeling is that there are probably as many use-cases for f.lux as there are users... and it would be great if it could be more flexible, and more straightforward to make adjustments.
Yeah, setting own times manually would be quite cool. Where I live days also get short in the winter - my daylight lamp is on until 7pm as well, although it can be dark outside hours before that.
I think some times that we've designed our presets for the night owl, and not everyone is a night owl, so we are working on it.
But the challenge is -- we'd like to make using the software more automatic, not less!
The "bedtime" mode is designed to allow your body to produce melatonin on its natural rhythm -- this happens >10 hours before you wake up, for most people (and maybe even earlier in the winter).
The melatonin rhythm is totally separate from a "cue" to go to bed, which is a separate and important thing (it's sort of why we did the backwards alarm clock). And as you say some people only spend 7 hours in bed and are quite happy about it. As it is, those notifications are sort of a prototype, and if people want us to we can make those cues a lot more customizable, and there could be a screen change too. Because I do agree that cue is pretty important.
I prototyped the notifications with a recurring calendar that was super-annoying (but I liked it better), and it would pop up and say "Get ready for bed now!" because I could do that when it was my schedule, but we had to make it more "objective" for this feature, so we weren't being totally rude for people who had to stay up late for some reason.
We have some ideas about how to let people say, "This is too early" or "This is too late" and have the software adapt. I think if we exposed an extra 5 parameters most people would find it too complicated. But we will probably have some more advanced parameters in a future version.