Valencia is famous especially amongst Erasmus students. The reasons are clear: a lot of partying - very well distributed - good weather, delicious food and cheap prices. Even though you're not an Erasmus student, consider the option of visiting Valencia, as here you'll find events for every taste and type of audience. Very few Valencians manage to skip the party, especially on Thursday, Friday and Saturday nights.
As in any other city of Spain, in Valencia people have lunch and dinner late, and this affects also partying time. The usual plan is to have dinner around 10 pm and then carry on with what here is called "previas", which is drinking before going out to dance. Entering the club sober is almost forbidden. First of all, you have to enjoy a few drinks with your friends, either by doing the "botellón" (very common among students, either in the street, in parks or using the trunk of the car as a mini-bar) or by taking advantage of the good weather and enjoying one of the many open-air terraces of bars and pubs that Valencia offers. There you'll find people between 25 and 35 years old, and with fuller wallets. These kinds of places always close between 2 and 3 am. That's when the clubs start to fill up. From then, people dance until 6, 7 or even 8 am.
The regulation is not excessively strict in regards of the closing time of the clubs, especially if these are in the outskirts of the city, as is the case of Barraca, one of the historical ones. Regarding the "previas" instead, you better be aware that the consumption of alcohol in the streets is forbidden, although the Policía Local usually closes an eye in places far from the neighbourhoods, such as the Paseo Marítimo, areas near the beach or the parks far from the crowded areas. Not even afterhours are particularly persecuted. If you are one of those who wants to dare, on Sundays from 8 am you’ll find music in places like Suite and Avenox.