Bullying in U.S. schools has been on a decades-long decline, suggests new research.

The analysis stems from an ongoing survey conducted at schools in Maryland from 2005 to 2014.

And national data also shows similar trends in recent years.

In the new study, more than 240,000 students in grades 4 through 12, from 109 schools in Maryland, shared their experiences with bullying.

Students were asked whether they had been a victim of bullying — physical, verbal, or cyber — within the past month.

They were also asked if they had witnessed someone else being bullied, and about their perception of bullying and the school’s climate.

“We found that bullying and related behaviors were decreasing, which indicated improvements in student behaviors and school climate,” Catherine Bradshaw, PhD, a professor in the University of Virginia Curry School of Education and senior study author, told Healthline.

Exactly why bullying seems to be on the decline among children and teens is “difficult to determine,” said Bradshaw, but “it is possible that policy changes as well as increased attention to, and awareness of, bullying nationally are factors that likely contributed to these improvements over time.”

The study was published May 1 in the journal Pediatrics.

Read more: The lasting effects of bullying »

Bullying decreasing nationally

Over the years, researchers found that between 13 and 29 percent of students said they had been bullied in the previous month.

About half had witnessed someone else being bullied.

Over the 10-year study period, the percentage of students who were bullied or had witnessed bullying decreased.

There were also declines in student reports of physical and verbal bullying, and cyberbullying.

During that time, student reports of feeling safe at school increased.

The new study is unique in that it uses multiple measures of bullying over many years. It surveyed both victims and perpetrators of bullying. It also included a wide age range of children and teens.

The survey also defined bullying the same way as the Centers for Disease Control and Prevention (CDC).

This includes actions like “threatening, teasing, name-calling, ignoring, rumor spreading, sending hurtful emails and text messages, and leaving someone out on purpose.”

The study counters public perceptions that bullying is on the rise, something fed in part by increased attention to this problem.

“The intensity of the discussion and the media coverage of [bullying] has maybe given people the impression that we’re experiencing some kind of an epidemic. But that’s not true,” David Finkelhor, PhD, director of the Crimes Against Children Research Center, and professor of sociology at the University of New Hampshire, told Healthline.

The new study focuses on only one state, but other research has a similar story to tell about the rest of the country.

Finkelhor noted that this includes surveys of school fighting, assault, and hate and bias crimes, which are “very difficult to separate” from bullying.

“They all point in the same direction — that the level of school bullying has been declining,” he said.

A 2014 report by Finkelhor, which summarized data from five national surveys, found that bullying has declined since the 1990s. It dropped less steeply since 2007.

These declines occurred across all demographic groups. Some studies in the report showed smaller decreases for girls, but others found similar declines for boys and girls.

Read more: Ostracism is just as harmful for the bully »

Why is bullying declining?

Pinning down the reasons behind the downturn in bullying can be difficult.

“It’s probably a complicated set of factors that intersect with why the [overall] crime rate has declined,” said Finkelhor.

Greater awareness and prevention programs — which he said have “increased tremendously over the last generation” — have helped.

But he notes that declines in bullying may result from better mental health treatment and access to psychiatric medication for children.

Reduced childhood exposure to chemicals like lead may also eliminate developmental problems that contribute to bullying.

Even technology, which has been blamed for enabling online bullying, can have a positive effect.

“Kids are more connected to each other and to sources of help by their technology,” said Finkelhor. “So it may be easier to get help.”

Increased surveillance equipment at schools and other places where children hang out can discourage bullying or make it easier to identify.

In spite of the improvements, Finkelhor said that some aspects of bullying have been difficult to target with prevention materials because they are “politically charged” — including bullying related to homophobia, gender, race, or ethnicity.

Bradshaw also emphasized the need to keep addressing the issue of bullying.

“Despite these positive trends, we should not reduce our focus on bullying,” she said, “as a large proportion of students are still victims or witnesses to bullying.”

She said monitoring efforts should continue in order to catch any plateauing or worsening of bullying. More research is also needed to make sure programs aimed at preventing and stopping bullying are effective.

And a community-wide approach can help.

“Parents and other adults also need to continue to keep communication open about healthy peer relationships and issues related to bullying and school safety,” said Bradshaw.

Read more: Bullying by peers is worse than abuse from adults »