These are trains with sleeping cabins and actual beds you sleep in. It's better than many hostels.
So as an individual traveling alone, you know your limits and can pretty much figure out if that way of travelling works for you. For a family, you are pretty sure at least one member of the family will have a rough night and complain in the morning.
A sure way to spend good night while travelling is to be very active during the day. You sleep much better if you have walked for 15 to 20km around a city to visit it than if you have been idle most of the time and taken taxis and buses whenever you could. Most lazy people don't understand that rest has to be earned.
And, yes, especially when time zones are involved, sticking to a schedule and getting exercise helps.