I like trains, but I was never refreshed and well-rested after a night journey in a sleeper car. It just twists and jumps too much (extra points for curvy tracks where you end up with your head slightly downwards from your body half of the time), plus many railway stations on the way have way too loud announcements, plus the border police likes to check even when it theoretically shouldn't (Schengen). I just can't manage to get deep uninterrupted sleep in such conditions.