I think most mainstream lines have a curfew of 1 am for under 18, at least ncl, rcl, carnival…As noted above, there is no official curfew on DCL (as far as I know). After frequent Disney cruises we sailed on Utopia of the Seas last weekend and I was surprised to see a "Junior Cruisers Curfew" in the app. For 17 and under it noted 1:00am.