Barcelona offers not only much for the culturally interested, also the the night-reveller come fully to their costs.
Start the party life leisurely. After lunch with the shopping bus "Tomb Bus" along the main shopping streets, then at about 21:00 to dinner in one of the many restaurants, then in a bar, after this from 1 clock in a club or disco.
In Spain, normally they eat very late, but some restaurants set on the tourist and the kitchen opens earlier. The bars are often close at 3 am before 1 am you do not need to go into a disco if you are not want to be just alone on the dance floor. You can then dance until the early morning hours, then in a café for breakfast.

Barcelona offers at any time of day a varied programme to the visitor.