The study's authors aren't suggesting that "hyper-texting" leads to sex, drinking or drugs, but say it's startling to see an apparent link between excessive messaging and that kind of risky behavior.
The study concludes that a significant number of teens are very susceptible to peer pressure and also have permissive or absent parents, said Dr. Scott Frank, the study's lead author.
"If parents are monitoring their kids' texting and social networking, they're probably monitoring other activities as well," said Frank, an associate professor of epidemiology and biostatistics at Case Western Reserve University School of Medicine.
Frank was scheduled to present the study Tuesday at a meeting of the American Public Health Association in Denver.
The study was done at 20 public high schools in the Cleveland area last year, and is based on confidential paper surveys of more than 4,200 students.
It found that about one in five students were hyper-texters and about one in nine are hyper-networkers - those who spend three or more hours a day on Facebook and other social networking websites.
About one in 25 fall into both categories.
Hyper-texting and hyper-networking were more common among girls, minorities, kids whose parents have less education and students from a single-mother household, the study found.
Frank's study is billed as one of the first studies to look at texting and social networking and whether they are linked to actual sexual intercourse or to other risky behaviors.
"This study demonstrates that it's a legitimate question to explore," said Douglas Gentile, who runs the Media Research Lab at Iowa State University.
The study found those who text at least 120 times a day are nearly three-and-a-half times more likely to have had sex than their peers who don't text that much. Hyper-texters were also more likely to have been in a physical fight, binge drink, use illegal drugs or take medication without a prescription.
Compared to the heavy texters, the hyper-networkers were not as likely to have had sex, but more likely to have been involved in other risky behaviors like drinking or fighting.
A Kaiser Family Foundation study found that about half of children ages 8 to 18 send text messages on a cell phone in a typical day. The texters estimated they average 118 texts per day. That study also found that only 14 percent of kids said their parents set rules limiting texting.
Other studies have tied teen texting to risky or lewd behavior. A Pew Research Center study found that about one-third of 16- and 17-year-olds send texts while driving. And an Associated Press-MTV poll found that about one-quarter of teenagers have "sexted" - shared sexually explicit photos, videos and chat by cell phone or online.
The latest survey did not ask what students texted or what they discussed on social networks.
One suburban Cleveland student said her texts involve non-sexual small talk with friends, homework assignments and student council bake sales.
"I text with my mother about what time I need picked up," said Tiara Freeman-Sargeant, a 14-year-old Shaker Heights High School freshman. She said she sends and receives about 250 texts a day.
Talking on the phone just isn't appealing to some teens, said her classmate, Ivanna Storms-Thompson.
"Your arm gets tired, your ear gets sweaty," said Ivanna, who also doesn't like the awkward silences.
Like her friend, Ivanna said she mostly gets A's. Whether kids who text do well in school or behave in a crazy, risky way is coincidental, she said.
"It depends on who you're talking to and whether they have their priorities straight," she said.