Originally Posted by
jackal
(unless market research proved it increases revenue because of the better hours and/or more comfortable ride)
Which is the key point, really. Nobody is going to take a sleeper leaving at 1am and arriving at 5.30am unless they have no other choice - and these days, they usually do. UK sleepers (on privatised railways) use coaches that have a maximum speed of 125mph, too, so they're definitely running slowly.