There currently is one option to travel by night train from Amsterdam (Netherlands) to Berlin (Germany), taking between approximately 8 and 9 hours: Namely the ES 453 operated by European Sleeper.
European Sleeper is a young Dutch startup connecting several European cities in Belgium, the Netherlands, Germany and the Czech Republic with their "Good Night Train". The sleeper cars offer comfortable and lockable compartments for one, two or three persons, each equipped with a washbasin. The service includes bedding, towels, toiletries and breakfast. A wake-up service is available. Choose between standard couchette cars with 6 berths or air-conditioned comfort couchettes for 5 people. The latter can be booked privately or exclusively for women. Blankets, bedding and mineral water are included, breakfast can be added for an additional fee. Compartments can be locked from the inside. The seating cars offer, as the most affordable travel option, 6-person compartments with guaranteed seat reservations. Breakfast can be booked for an additional fee, drinks and snacks are available on board.