Whether you visit Reykjavik in the summer with 24 hour sunlight or in the freezing cold winter when the capital sees only few hours of daylight, you can always count on a vibrant nightlife.
You couldn't possibly plan a trip to Iceland without learning about the crazy Reykjavik nightlife along the way. Reykjavik at night is a place where mass public drunkness is completely socially acceptable from Thursday evening to Sunday morning, even though it's technically illegal. The locals are usually not in a hurry to get to the downtown area, so don't expect to see big crowds out there before midnight. When they eventually get there however, they will party until the break of dawn. You may stay out just as long as the locals at bars, clubs and pubs.