Dr. Anis Rehman, an internal medicine specialist and consultant to the Sleep Foundation, says that about half of kids ages 3 to 6 experience frequent nightmares, and about 20% of kids ages 6 to 12 do.

Easy ways to improve sleep hygiene include ensuring that your child’s bedroom is a quiet, calm and darkened place to rest. Too much mess can make their minds too busy at bedtime, so clear away ...