Now that children are back in school, it is important to make sure they get enough shut-eye, sleep experts say.

"No matter the age, children report improved alertness, energy, mood and physical well-being when enjoying healthy, consistent sleep," said Dr. Ilene Rosen, past president of the American Academy of Sleep Medicine (AASM).

"Back-to-school time provides families with a perfect opportunity to re-evaluate their sleeping habits and establish healthy routines to ensure sufficient sleep," she added in an academy news release.

Different age groups require different amounts of sleep on a regular basis:

• 4-12 months old: 12-16 hours (including naps).
• 1-2 years old: 11-14 hours (including naps).
• 3-5 years old: 10-13 hours (including naps).
• 6-12 years old: 9-12 hours.
• 13-18 years old: 8-10 hours.

It's especially important for high school students to get enough sleep because sleepy teens do much worse in school than those who are well-rested, according to the AASM.

Research shows that sleep-deprived teens may be more easily distracted and have more trouble recalling information than those who get enough sleep, the academy said, and that not getting enough sleep is associated with attention, behavior, and learning problems.