My girl works night shifts stocking in the same store I work first shift in, and when they have call offs or exceptionally large truckloads the night manager calls me around 10 or 11 pm and asks if I want to work any or all of a night shift that evening, as pure overtime. It's fun for a few hours but, much like staying up late, it becomes stale and difficult to continue past about 3-4am. Most of the novelty comes from me being familiar with the store during the day, and how different it is at night when no one is there.