I ride a lot at night to train in January and February. (California has it's perks)
Like others have said, once you get your lights and reflective gear sorted out I think night riding is very safe.
My experience has been that training rides starting about 7:30 or 8PM are great because there are so few cars on the road.
Most people are home on the couch watching the tube during "prime time".
Prime for TV and prime for night riding too.
The very few cars on the road argument went a long way towards helping my wife feel better about my safety.