"PeterC" wrote in message
...
sometimes forget
to switch one of in daylight because it makes no difference to the
perceived
colour.

That could be because the daylight bilb isn't bright enough to matter
and it;s contributing little to the ambient light level.

It's in an Anglepoise-type thing and a GU10 lamp, so the intensity is
pretty
good. As dawn breaks and the light increases I sometimes don't really
notice
and eventually they merge. Switching off is very noticeable in intensity
but
not in quality, just a small change.

At my last house, my study was lit by a 150W-equivalent (25W, I think) CFL
bulb - overhead pendant with a shade.

I sometimes forgot whether the bulb was on or off, because it matched the
daylight coming in through the window.