Infants and toddlers in Japan have shorter sleeping hours than those in the United States, Europe and other parts of Asia, a sleep psychologist said Wednesday.

Children in Japan who are 3 or younger sleep for an average of 11 hours and 37 minutes, while those elsewhere in Asia average 12 hours and 16 minutes and tots in the United States, Europe and South America get 13 hours, said Jodi Mindell, psychology professor at Saint Joseph's University in Philadelphia, at a news conference in Tokyo.

"When you are children, how much sleep you get is the most important thing," Mindell said.