Most airports offer passengers to use lounge zones for € 30–50 per night. There are few people, there are food and drinks, good Internet-connection, and many chairs and couches. Sometimes there can even be a shower and special rooms where you can sleep. All these things are free for lounge-zone visitors. If for some reason you have to spend more than 6 hours in the airport, this is a great way to save money and not spend it on food or a hotel room.