How common is obstructive sleep apnea is grade-school children?

5% or more: Estimates as high as 5% of all school-age children have sleep apnea. This number certainly will go higher given the unfortunate epidemic of childhood obesity. Obstructive sleep apnea can cause all sorts of problems and children with it are frequently mistaken for having attention deficit disorder.

Sleep apnea: This can be a very common problem- do they grind their teeth, or are there any behavior problems. Have they had their tonsils and adenoids removed?

Common: Up to 5%. If you suspect this, see a pediatrician with expertise in sleep apnea.