Don't know if it has effects on sleep, though anecdotally I sleep very well. However before using f.lux I experienced headaches from time to time after long days in front of various screens. It wasn't a regular occurrence but I'm pretty sure it was related to those long hours.

Since I started using f.lux all day (not just at night) several years ago those headaches have a been a thing of the past - it basically doesn't happen anymore.

I know f.lux is intended to be used in dark environments but since I rarely do color-sensitive work and prefer the lush, warmer color temperature (3800K for me), I see no reason to change my all-day use.

I think for something as simple as Night Shift, "try it yourself and see" is a valid approach. Even if it's a placebo effect, it's still an effect!

Anecdotally, Flux + Night Shift dramatically improved my longstanding insomnia. But that's just my anecdotal experience

If it helps people to improve their hygiene, by placebo effect or otherwise, then that's a good thing.

However, I ask because I did try it for several months, and did not notice any effect other than the minor irritation of having to keep turning it off when I wanted to watch a film in the evening (and the constant malfunctioning of f.lux – although hopefully those issues would not be present in Night Shift).

I'm not sure I would be able to detect an improvement even if there is one though - there's too many confounding factors. So I'd like to see some evidence so I can make an informed decision.

Yeah, I would be curious to see some real studies on that as well, I suspect that having a bright screen in your face is the problematic part, and that color temperature only make a very marginal difference, if any at all.

But honestly, I use it because I like it, not for any positive effects it may have on my sleep. It just makes it more pleasant to look at screens after nightfall. Also, seeing the screen change is a very pleasant "hey, stop looking at Twitter/HN and go to bed!" reminder.

Flux's biggest benefit for me was just making sleep something I thought about, what really works for me is not using screens for a good bit of time before bed. I can't quantify the days I wake up feeling great very well but I do feel the difference if I go to bed overstimulated from too much time on screens, arguing on the internet or whatever.

Ganglion cells[0] are sensitive to blue light and produce melatonin, one of the few sleep regulating hormones.

[0] https://en.wikipedia.org/wiki/Intrinsically_photosensitive_r... nal_ganglion_cells

For me, it is not about sleep. If I disable Flux at night, it hurts my eyes.