That about sums it up. It's for you to sit and watch your fish do their thing. Some fish really enjoy having a few hours of moonlighting. Many of them are very active during that time (Otos, Loaches for ex). Others are said to be induced to spawn.
I would keep the intensity low, and only run it for a couple of hours so your fishies still get a bit of a dark period.
It shouldn't affect the plants at all.