Your plant does not search for the light in that period as it knows it is not there and it does other things in it chemical proccesses as the_mole said. Plants never sleep, they keep on growing and growing, even in dark.

Cyber : If plants slept in the dark, where the hell does your bud come from? Do you think it comes magically?

Not to be rude but if you have a grow thats kind of sad that you yourself do not possess such knowledge.