Yes, I've got it set to auto-switch between Night and Day modes. I presume it does this by reference to its sunset and sunrise calculator. I haven't tried playing with the colours yet – well, I have a vague memory of doing that, but can't remember what I altered – but I think I'll leave them as they are for the time being, they seem ok.
So 'Stay on' but on zero power seems to be the way to go, toggling as necessary. Thanks all!