As far as I know, no. But hypothetically, yes, as long as you have another way to get into your room then you could destroy a ticket.

[By the tone of her voice, she doesn't recommend doing this, since the ticket does have a few other uses.

As for the sleeper cabins...]

Not much of a choice here. Even if you go to sleep somewhere else or stay up late, the train just forces you back to your room by a certain point at night. The good news is that you're only forced to be there during the required sleep hours at least.