San Pedro welcomes tourism but not late-night revelers. There's only one bar and no alcohol is sold after 1am. Nights are cut short by travelers with early tours: waking for a 4am jaunt to El Tatio is enough of a headache without a hangover!
However there's a cozy bar-cum-restaurant scene, with travelers swapping stories around fires and enjoying happy hours.
There's a well-kept public secret here: rave-like parties in the desert occur on a regular basis, although they aren't advertised due to police crackdowns. It's all word of mouth, so ask around town to see what's happening and where.