https://justgetflux.com/faq.html
 
And if you did, were there any problems encountered if it dimmed/changed colour during an actual recording session (with Sonar)
 
Thanks,
Wei Liang

I use it and have not noticed any issues with Sonar. Is there something specific I can do to test?

I've used f.lux for a couple of years and have never had any problems with Sonar. Apparently its CPU usage does ramp up during the day/night transition so I guess that could impact a CPU heavy project. My advice would be to be aware of what time the transition happens, and maybe turn it off temporarily until you've finished tracking. Otherwise it's an excellent app which has been great for my eyes (and sleep patterns). 

No specific questions Max, just needed some reassurance that it wasn't going to cause problems when using Sonar before installing it.  Thanks Max and Sharke for replying - I will try it (and hopefully sleep better too).
 
Wei Liang

I love it. No issues. It's a real eye saver I tell ya!

I think I posted about this a while ago but it's also a good idea to turn your monitor up to maximum brightness and dim it via f.lux. The reason is because modern LCD monitors achieve lower brightness levels by turning the pixels on and off to a pulse. The lower the brightness, the lower the pulse width. So if you set your monitor brightness control to anything less than 100%, the screen flickers. This flickering can cause eye problems and headaches. 
 
Adjusting your screen's brightness at the software level is totally different, there is no pulsing. This was a revelation to me because the first thing I've always done when I get a new monitor is turn the brightness down with the monitor controls - 100% is usually way too bright. I had no idea this might have been contributing to my eye fatigue and headaches, you'd think the opposite would be true. 
 
f.lux can reduce your monitor brightness via two hotkeys, Alt-PgUp/PgDn. This is different from the color warming that is f.lux's main function - it doesn't yellow the screen, it just lowers the brightness. So I have f.lux both warming the colors at night AND lowering the brightness at all times. I feel so much better for it. 

I've been using it for probably as year now - great app. Easy on the eyes.

I like it too. I also use the Twilight app on my Android phone(yes it is still the same Ace 2 phone). I meant to upgrade but I haven't found a cheap yet good phone. I almost bought the moto e and also thought about the moto g but there were some features missing on the moto e and the g version got feedback having made the newer g version somehow worse than the earlier one.