Your mind is surprisingly busy while you snooze. During sleep you can strengthen memories or "practice" skills learned while you were awake (it’s a process called consolidation).
"If you are trying to learn something, whether it’s physical or mental, you learn it to a certain point with practice," says Dr. Rapoport, who is an associate professor at NYU Langone Medical Center. "But something happens while you sleep that makes you learn it better."
In other words if you’re trying to learn something new—whether it’s Spanish or a new tennis swing—you’ll perform better after sleeping.
'We are such stuff as dreams are made on; and our little life is rounded with a sleep." William Shakespeare