When Interrailing through Europe, sleeping on the train is a popular strategy to save time and money, and there are several ways to do it. The most common "sleep" happens on Night Trains (like the ÖBB Nightjet or the European Sleeper), which are specifically designed for overnight travel. These trains offer three levels of comfort: Seats (the cheapest, but hardest to sleep in), Couchettes (shared compartments with 4–6 padded bunks and basic bedding), and Sleeper Cabins (the most expensive, featuring proper mattresses, washbasins, and often breakfast). If you have an Interrail Pass, you don't pay for the full ticket, but you must pay a mandatory reservation fee for your bed, which can range from €20 for a couchette to over €100 for a private sleeper. Another option is simply taking a late-night regional or high-speed train that arrives very late; however, most standard daytime trains do not have beds, so you would be sleeping in an upright seat. A major "pro tip" for Interrailers is the "one-day rule": if you board a direct night train that departs after 7:00 PM and arrives after midnight, it only uses one "travel day" on your pass (the day of departure), making it a highly efficient way to travel long distances like Paris to Berlin or Munich to Venice while essentially getting a "free" night of accommodation.