There is no direct night train — or sleeper — between London and Paris. The Channel Tunnel's passenger service is Eurostar, which runs fast daytime trains (London St Pancras to Paris in about two hours twenty), not an overnight. So you cannot sleep your way from London to Paris on a single train. What you can do is combine a daytime Eurostar with a European night train onward from Paris. Paris is a hub for overnight services: from there, ÖBB Nightjet and connecting operators run to cities such as Vienna, Munich and beyond, and European Sleeper is expanding the continental night-train network. The usual pattern for a UK traveller is Eurostar to Paris (or Brussels) by day, then a night train onward into Europe, with a comfortable connection time to spare. Book the Eurostar and the night train as separate legs, allowing plenty of margin between them. Routes, operators and timetables change, so check current services with Eurostar and the relevant night-train operator when planning, and don't rely on a tight same-station connection.
Sources: seat61.com · europeansleeper.eu
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