About twelve hours. We currently have tickets available only for first class on the express train. If you’d like, you can choose a sleeper on the overnight train which is a bit less expensive.
The year before last my friend ran into a considerate thief on the train who crept into his sleeper in the dead of the night, took away his leather shoes and left a pair of female slippers in their stead.
Still, if late sleepers want to lose a few pounds, they can go to bed earlier than they usually do, thereby reducing their chances of taking snacks before bedtime.