For all rail schedules in Italy, check the Italian national rail site, Trenitalia, and input your travel details. They work 60 days out, but you can try checking earlier dates on the same day of the week that you plan to travel...they shouldn't change that much. At this point, the train that will get you the most sleep appears to be the 768 Scilla...you take a regional train out of Naples at 10:20 pm, catch the overnight train at Caserta at 12:35 am, then get into La Spezia at 7 am, where you change for Vernazza. It does not go thru Rome. Any of the overnight trains from Rome leave around 11 pm and get into La Spezia at 4 or 5 in the morning, where you wait for your connection to Vernazza....not a lot of sleep, and some early-morning transfers! There are a couple of overnight trains from Rome that go thru Florence...but the journey time is only 2-3 hours, so you certainly won't sleep on those!