Night trains usually have sleeper compartments, which should be reserved in advance and which add cost to a Eurail pass or European train ticket, even one for a night train. You can also sleep in a regular seat on a night train at no extra cost.

Overnight trains in Europe, such as the ÖBB Nightjet or the Caledonian Sleeper, function like "hotels on rails," allowing you to travel across the continent while you sleep. When you book, you choose between three levels of comfort: Seats (the cheapest, standard train seats), Couchettes (shared compartments with 4–6 fold-down bunks and basic bedding), or Sleepers (the most comfortable, offering 1–3 proper beds, a washbasin, and sometimes a private shower/toilet). In 2026, most berths are sold individually; if you don't book an entire compartment, you will share with other passengers of the same gender. Upon boarding, a steward typically checks your ticket and passport so you aren't disturbed at border crossings. In the evening, the steward or the passengers themselves convert the seats into beds. Most modern sleepers provide a small "welcome kit" with earplugs and toiletries, and many include a continental breakfast in the morning. This system is a favored "sustainable" alternative to flying, as it saves the cost of a hotel night and delivers you directly to the city center.