At these ages, with social, school, and family activities, bedtimes gradually become later and later, with most 12-years-olds going to bed at about 9 p.m. There is still a wide range of bedtimes, from 7:30 to 10 p.m., as well as total sleep times, from 9 to 12 hours, although the average is only about 9 hours.read more >>