Vacation season is upon us. But a school break doesn’t necessarily mean teens are roaming free.

A new poll finds that less than half of U.S. parents feel comfortable leaving their teenager alone in a hotel room while they grab breakfast. Fewer than one in three would let their teen walk alone to a coffee shop. And only one in five would be okay with their teen wandering solo around an amusement park.

Those results, released June 16, are troubling, says public health expert Sarah Clark. She codirects the C.S. Mott Children’s Hospital National Poll on Children’s Health. Teenagers, she says, need freedom to develop the confidence that they can navigate the world on their own.

The poll surveyed more than 1,000 U.S. parents of children ages 13 to 18. It was conducted by the Mott Poll team at the University of Michigan in Ann Arbor. This group regularly surveys a subset of 50,000 households. They ask about issues related to parents’ views and children’s health.

For years, researchers and policymakers have been sounding an alarm. They’re concerned that children and teens have fewer chances to play and explore without adults around.

Psychologist Peter Gray is part of a team that wrote about this almost two years ago in The Journal of Pediatrics. For instance, compared with previous generations, children across much of the Western world are less likely to hold part-time jobs. They also are less likely to walk or bike to school alone. Parents report increasing discomfort with letting their kids engage in risky, unsupervised play, other research shows.

That loss of freedom coincides with a decades-long uptick in teen mental-health problems. Showing whether one causes the other has proven difficult. Many other aspects of childhood have changed too, researchers note. Technology use is a big one.

But squelching childhood independence undermines normal development, says Gray at Boston College in Massachusetts. That development includes a teen’s innate need for close peers and partners. “It’s absolutely no surprise to me that we are seeing these dramatic rises in anxiety, depression, even suicide among teenagers.”

Vacations present an ideal time for teens to practice independence, says Clark. Parents can plan where to stay to give teens more freedom. And they can set guidelines. For example, they can ask their teen to text when they get to their destination. Or families can agree on when and where to meet up.

Clark does sees some promising signs. Two-thirds of the parents polled felt confident their teens would follow their rules even without them around.

The goal shouldn’t be to protect teens from all dangers. Instead, says Clark, adults need to help them practice life skills. This might mean riding public transit, knowing what to do when approached by a stranger or ordering a sandwich on their own.

“If we reach some families and just approach this upcoming summer a little differently, I feel like that’s a big win.”