Teens who swap 120 or more text messages a day are more likely to indulge in sex, drinking and drugs, according to a new study.

These “hyper-texters” are almost 3.5 times more likely to have had sex and 90 percent more likely to report having four or more sexual partners, the Case Western Reserve School of Medicine study showed.

“The startling results of this study suggest that when left unchecked, texting and other widely popular methods of staying connected can have dangerous health effects on teenagers,” said Case Western physician Dr. Scott Frank, who surveyed more than 4,200 high schoolers at 20 high schools.

Other experts on Tuesday emphasized that one habit does not lead to the other, but admitted the correlation is not surprising.

“What we’re seeing is an increase in impulsive behavior. Social networks, texting, all these have immediate gratification,” said New York licensed clinical psychologist Joshua Rosenthal. “That’s the skill kids are losing, the ability to delay gratification.”

The trend also involves a lack of self-regulation, added education psychologist Dr. Jane M. Healy, author of “Different Learners.” “It’s been my contention that most of the electronic behavior these kids are addicted to [leads to them] not considering the consequences of their actions.”

Dr. Kathleen Bogle, a sociologist and author of “Hooking Up: Sex, Dating and Relationships on Campus,” said the link between excessive texting and unhealthy behavior can also be explained by popularity and peer pressure.

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“Students who are more outgoing or social are more likely to text and also to do that whole list of things: sex, drinking,” she said.

Ultimately, Mom and Dad can take responsibility and keep their children off of a self-destructive path, a parenting expert said.

“Parents should be setting a limit on it all and letting their kids know their expectations of their behavior,” said Darcy Jacobs, executive editor of Family Circle magazine. “They should be helping them set boundaries.”

Open communication with teens and a sincere interest in their lives — including what they’re texting about — will also help them develop better judgment, Jacobs said.

Especially since “social networking and texting are just going to be part of culture at this point,” said Dr. Renee Clauselle, a New York-based child psychologist, who added that parents should monitor their kids in cyberspace just as they would on the playground.