If your child is tired all the time, her immune system may be too sluggish to fight off bad bugs. Unfortunately, a third of all kids don't get as much sleep as they should. Ideally, babies need up to 18 hours a day, toddlers and preschoolers need 12 to 14 hours, and grade-schoolers should get 10 to 11 hours. It's probably not practical for your child to wake up later, so if she's not hitting these numbers, make her bedtime earlier.