The vibration will be impacted by two major factors: Whether the engines are running at or near full power, and prevailing sea conditions. We were on the 9-night Greek Isles Cruise in June and for the first two nights, the vibrations were something - but we still had a great night of sleep. Then we had a few consecutive days and nights when it wasn't an issue at all. Then we had a rougher day when wind and sailing conditions were a bit more rough than expected... and all was quiet on the last night