I'm planning a trip to Europe that may involve an overnight train ride. We're considering taking along our 4-year-old daughter and 1-year-old son. Can anyone speak from experience or other wisdom to the question of how to best arrange sleeping space for the 1-year old? My first thought is to strap him into his car seat and let him sleep there, but I'm not sure how well this would work for overnight. Any better ideas?

With my wife's parents along, we'll have enough people to fill a 6-seat couchette, so we won't need to worry about disturbing the sleep of strangers sharing the compartment. But to avoid keeping those in our party awake, I might consider the Benadryl route (yes I know to test before hand to make sure it won't induce hyperactivity).