Summer is winding down, and the school year will be here soon, which means parents and children need to make sure they are getting a good night's sleep.

According to a National Sleep Foundation poll, 65% of Americans report having difficulty falling asleep, waking during the night and waking feeling tired at least a few times each week.

What should parents and children know about sleeping right?

"Adequate sleep is necessary for optimal functioning," said Kelly C. Byars, an associate professor of clinical pediatrics at Cincinnati Children's Hospital Medical Center, who directs the Behavioral Sleep Medicine Program there.

According to Byars, here is the amount of sleep different age groups need each night:

• Infants (2 to 12 months old): 13 to 17 hours

• Toddlers (1 to 3 years old): 12 to 14 hours

• Preschoolers (3 to 5 years old): 11 to 13 hours

• School-age children (6 to 12 years old): 10 to 11 hours

• Adolescents (13 to 18 years old): 9 to 9.5 hours

Byars and Dr. Samuel Dzodzomenyo, medical director of the Pediatric Sleep Center at Dayton Children's Medical Center in Dayton, Ohio, said sleep helps children to do their best in all aspects of the day, including in athletics, academics and social interactions.

Sleep gives the brain a chance to reorganize and store information gathered during the day more efficiently, reduces anxiety, helps the body recuperate physically and promotes growth in general, they said.

On the other hand, not getting a good night's sleep may lead to mood and behavior issues; accidents and injuries; memory, concentration and learning problems; slower reaction times and compromised health.

Several obstacles stand in the way of a good night's sleep for children, according to experts.

These obstacles include the lack of an appropriate bedtime; anxiety at night; refusal to go to bed; late meals or exercise; using light-emitting electronics such as a television, a computer or video games; medical conditions such as gastroesophageal reflux disease and asthma; and intrinsic sleep disorders such as obstructive sleep apnea, Byars and Dzodzomenyo said.

Most childhood sleep problems can be effectively treated with behavior modifications alone. Dzodzomenyo and Byars suggest that children take these steps to get the best rest:

• Wake up and go to sleep at approximately the same time every day of the week, including the weekend.

• Napping should be developmentally appropriate. Too long or too frequent naps may disrupt sleep. For children requiring nap time, avoid naps after 3 p.m. For older children, napping during the day should be avoided.

• Eat regular meals, and do not go to bed hungry.

• Several hours before bedtime, eliminate all foods and drinks containing caffeine, such as most colas, chocolate, coffee and tea.

• Children should learn to fall asleep independent from their parents and sleep in their own beds by themselves.

• Vigorous activity should be avoided for one to two hours before bedtime. But mild exercise up to four hours before bedtime is appropriate and may help children fall asleep.

• Spend time outside each day.

• Make sure that the bedroom is a comfortable temperature -- cooler than 75 degrees -- during the night.

• Restrict activities in bed to sleeping only. Avoid watching television, reading and playing games.

• Keep the sleeping environment relatively free of loud distractions.