http://www.voyages-sncf.com/billet-trai ... tats?hid=5
I hope that site works. (if not, type in http://www.voyages-sncf.fr and type in Paris to St. Jean Pied de Port, date and time desired etc.)
There is a night train from Paris Austerlitz at 23h10 (on the 28th) arriving at 6h33 in Bayonne...