Rabbits are crepuscular by nature - that is, they're most active at dawn and dusk, and less active at night and mid-day. Also, they can see pretty well in low-light conditions and in the wild rabbits would live in underground warrens.
All that's saying that they really don't need artificial light at night - if anything, it would extend the period that would be "dusk" to them, and thus let them be more active when they would naturally be asleep (or, at least, less active). For obvious reasons I've never had a discussion with Natasha about what she prefers, but I don't leave a night light on for her and she seems perfectly happy.