There currently are a variety of options to travel by night train from Paris (France) to Briançon (France), taking approximately 11 hours: Namely the INTERCITES DE NUIT n° 5789 and the INTERCITES DE NUIT n° 5787. These lines are operated by SNCF.
In France, a few night train lines are operated by the state-owned SNCF.
These night trains typically feature seating carriages and couchette carriages in first and second class.
The couchette carriages offer space for up to four people per compartment in first class and six people in second class. The berths are simply designed in both classes and are about 1.9 meters long.
Yes, for more privacy, entire 4-person compartments can be booked exclusively. This can also be done for a group.
First class berths are slightly wider than in second class and there are only four berths per compartment. Advantage of first class: In Paris and Toulouse, there are showers at the stations for first class passengers. In second class, six travelers share each compartment. For cyclists, it's possible to bring a bicycle in second class for an additional fee of 10 euros.
You should bring your own food as there is no restaurant on board. Alternatively, you can pre-order meals and drinks or eat before departure. First class travelers receive a small breakfast. Each passenger receives a night kit with refreshing towelette, dental cleaning tablet, sleep mask, earplugs, and water.