I found that my windows 8.1 cannot sleep. When I typed "powercfg -requests" command in cmd, I figured out Flux wakes windows up. So I must exit from Flux. How can I have Flux active and also do not miss sleep mode?
I also found the same problem. I had already solved by switching-off (if they are being switched-on) all options of selection 'Connected Lighting'. Right-click at flux icon on system tray, and choose 'Options and Smart Lighting...'. So the flux.exe should disappear in the requests list and you can sleep you PC.
Ps. my flux's version is 4.55