I never thought there were ''nights'' on the Enterprise. Off-duty hours, certainly. But no dimmed lights. That might explain McCoy's grouchiness.
Didn't 'The Conscience of the King' suggest they dimmed the lights on board to simulate night?
This is a concept that got kind of lost after the production got more and more rushed.
One would have to assume that this would happen more in the non-operational areas of the ship. Although at the end of Data's Day
, they show Data taking the con for the night watch (makes sense to have your android Lt Cmdr do that!), and the ambient light on the bridge dimming all so slighty.