WEDNESDAY, Aug. 31 (HealthDay News) -- Although many kids stay up late on long summer days, once school starts in the fall they should return to their normal sleep routines, according to experts at University of Alabama at Birmingham (UAB).

Pointing out that adequate sleep is essential to a child's academic success and overall well-being, the researchers said that 3- to 5-year-olds need at 11 to 13 hours of shut-eye per night. Five to 12-year-olds need at least 10 or 11 hours a night.

"From memory to judgment, attention span, emotional stability and even immunity, sleep deprivation negatively affects school-age children," Dr. Kristin Avis, UAB assistant professor of pediatrics and a sleep specialist, said in a university news release.

"As for adolescents, it's a common myth that they need less sleep, and can handle only seven or eight hours, but they actually need nine hours of sleep," Avis said. Adolescents are typically the most sleep-deprived population in school, she added.

A poll by the National Sleep Foundation revealed that 60 percent of children under the age of 18 complained of being tired during the day. Moreover, 15 percent admitted to falling asleep at school.

Anticipating the first day of school, experts say children should start going to bed earlier to avoid these feelings of daytime sleepiness and ensure a smooth transition back to the classroom.

"About a week ahead of school starting, begin to back up their bed-time and wake-up times. This incremental change may start off rough, but it will get easier and ensure they are not miserable on their first day at school," Dr. Stephenie Wallace, a UAB assistant professor of pediatrics, explained in a news release.

Since missed hours of sleep can add up and have detrimental effects on children, UAB experts recommend that parents remove electronic devices from their child's room, making it as calm and peaceful as possible.

"On average, there are three to four electronic gadgets in a kid's room," said Avis. "It's been shown that even sleeping with a television on deprives them of 20 minutes of sleep per night, which may not sound like a lot, but adds up over a week's time."

The UAB experts noted they are conducting additional research on how poor sleep affects children, as well as how sleep deprivation among kids is linked to safety issues.

More information

The National Sleep Foundation provides more information on children and sleep.