The less sleep teenagers get, the more ill-equipped they are to navigate the challenges of adolescence, health experts say. Yet the amount of sleep that teens are getting each night is the lowest it's been since 1991, new research shows. For U.S. adolescents and teenagers in grades eight, 10 and 12, sleep levels have steadily decreased over the years from 1991 to 2023, according to researchers from the University of Minnesota, Columbia University and the University of Michigan.