This means that school nurses often must coordinate care for students and communicate with staff and families without assistance. 

"Our findings show that many nurses may be doing this without the support they need," Kelly Sarmiento, one of the study's authors, said in a news release.

A concussion is a mild form of a traumatic brain injury that can affect memory, balance, concentration, mood and sleep. Most children who experience a concussion may go back to school within one to two days, though they still may have symptoms, such as headaches, vision issues and fatigue, the Centers for Disease Control and Prevention says.

The Brain Injury Association of American – which collaborated on the study with Indiana University School of Medicine – has a series of evidence-based recommendations for concussion policies for schools. But the researchers found that "schools in higher-poverty communities, schools with larger proportions of non-white students and smaller schools were less likely to report having concussion policies, which may point to resource and capacity differences," Dana Waltzman, the study's co-author, said in the release.

Concussions are caused by blows or impacts to the body or head and often occur from falls. People do not always lose consciousness with concussions. Symptoms may emerge immediately or gradually, which can make concussions tricky to diagnose, the Mayo Clinic says.

Common symptoms include headaches, dizziness, vomiting, fatigue, drowsiness and blurred vision. People also may feel like they are in a fog and may not remember what caused the concussion or how it occurred.

Others may notice that the person with a concussion seems dazed, repeatedly asks the same question or slurs speech.

Longer-term symptoms may include emotional changes and depression, sleeping troubles and sensitivities to light and noise.

Any child who has a head injury is advised to see a health provider within one to two days or get emergency care if there is repeated vomiting, a loss of consciousness, changes in physical coordination, seizures or convulsions and other issues, the Mayo Clinic says.