In U.S. railroad terminology, a troop sleeper was a rail car which had been converted to serve as something of a mobile barracks for transporting troops distances sufficient to require overnight accomodations. This method allowed part of the trip to be made overnight, reducing the amount of transit time required and increasing travel effeciency.

There were not an adequate number of Pullman cars available to meet the massive need for troop transit created by World War II, so many troop sleepers were converted boxcars which were converted back into boxcars after the end of the war. Subsequent wars have not created the need for such an arrangement, partially due to the much smaller level of manpower involved but primarily due to the wider use of aircraft for long-distance transportation of troops.