Children often say returning to school is a pain.

They may mean it figuratively, but doctors at Nationwide Children's Hospital said they see more cases of headaches -- with greater severity -- in the fall.

More than 20 million children suffer from migraines or tension headaches, according to a study from the hospital.

"For various reasons, we definitely see an uptick in our headache problems right now," said Ann Pakalnis, who runs the headache clinic at Nationwide Children's Hospital.

Pakalnis said one of the reasons is a lack of sleep as kids change from a summer schedule to getting up and ready for school.

She also said parents should not over-medicate for headaches.

"It's very important that the parents discuss that with the children and realize that if they are taking medication that frequently, then the headaches really do need to be evaluated thoroughly," she said.

She said some signs that a child needs to see a doctor include skipping fun activities because of a headache or pains that start in the back of the head or neck.