Anger nap

While the 40 participants initially spent equal time attempting to conquer the unsolvable puzzles the scientists put before them, a one-hour nap made people more likely to continue spending time on the problem, while non-nappers (who watched a nature documentary for an hour instead) were more likely to give up. The nappers also reported that they felt less impulsive after having a snooze. The subjects had kept a consistent sleep schedule for the few days before the study, and the groups were randomized to control for age, habitual feelings of sleepiness, and other factors.