There currently is one option to travel by night train from Tarbes (France) to Paris (France), taking between approximately 12 and 13 hours: Namely the INTERCITES DE NUIT n° 3740 operated by SNCF.
The French national railway SNCF serves several night train routes within France.
SNCF night trains are equipped with standard seating carriages and couchette carriages offered in two comfort classes.
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.