I've taken the overnight train from Edinburgh to London. It arrives early morning but you could stay in the train for several hours while it was in the station.

I've taken the overnight train from Edinburgh to London. It arrives early morning but you could stay in the train for several hours while it was in the station. Quite comfortable. On the other hand, I took an overnight train from Wuhan to Beijing. It was crowded, the cars not so modern, and I didn't sleep all that well. The high speed rail train between those two cities was a much shorter and better experience.