Meat Loaf had the right idea: Next time you’ve got a big decision to make, go to bed—odds are, you’ll have a better answer when you wake up.
Scientists at the University of Bristol implanted electrodes in the brains of male rats. After recovering from the surgery, they (the rats, not the scientists) alternated sleeping, resting, and roaming free while scientists tracked what info they’d kept or dumped while asleep.
They (again—and much to their chagrin—the rats, not the scientists) were then euthanized and their brains probed.
The takeaway: During sleep, the brain swiftly sorts the day’s experiences and files the meaningful ones to the memory, essentially “decluttering” the mind and allowing it to focus better on what’s important—like making crucial decisions.