It's 700 kilometers to Hue and the only half comfortable way of traveling there is the night train. The alternative a night bus is only for when you are really desperate.
We left exactly on time at 3.45 in the afternoon and arrived spot on at 6.15 the next morning. As you can see from the photos there are four berths per cabin and I shared mine with a Chinese couple. The big benefit of travel by train is that you can get up and walk around to stretch your legs and on a sleeper train like this you can stretch out and try to catch a rest. I still didn't sleep much but that has probably more to do with me then the train.