Partying isn't a weekend affair anymore. For a growing number of expats, primarily young adults, though not exclusively, life abroad revolves around late nights, spontaneous drinks, and afterparties that spill into the next day. From Lisbon to Bangkok, Barcelona to Bali, you'll meet carefree night owls who refuse to save their fun for the weekend. But how do they manage this pace? And more intriguingly, what drives this almost essential need to go out so often?