They say you shouldn’t go to the supermarket hungry. A new study says you shouldn’t go when you’re tired, either. The day after a night of no sleep, researchers sent 14 people to a mock supermarket with 50 bucks and a mission: Buy as much as you can. Compared to what they bought when they were well rested, the exhausted participants purchased 9 percent more calories and 18 percent more total food by weight. The research team believes that the effect of sleep-deprivation on high-level thinking leads to impulsive decision making at the checkout counter.