Yes, the key is "out of sight, out of mind". Just don't leave anything in view that you consider "valuable". As stated above, the SCAs do a good job monitoring each car, but I would not leave a watch or computer in plain sight when leaving your room. I even sometimes take my computer (it's a small lap top) with me, since it has a lot of business info on it. There just is not that much traffic of people walking around in the sleepers-other than your fellow sleeper passengers.