About 10 percent of kids and teens struggle with anxiety disorders. It is the most common psychiatric illness, but it often overlooked by loved ones, particularly during back to school time. Health reporter Erin Billups has more on how to spot and respond.

As far back as she can remember, Selena Padilla says heading back to school after summer break was always a rough time.

"Some years, the first day I would just be sobbing," she says, "and that happened every school year as far as like this really powerful, like, anxiety. Like, why do I feel this way? Especially as I got older, I'm like, why do I continue to feel this way?"

When she mentioned her feelings to her mother and guidance counselors at school, they would simply tell her it was normal.

As her anxiety intensified, her desire to learn dropped.

"I just, I had no motivation to just want to be in school because I just thought, like, I have so many other issues and a lot of people don't really focus on teenage issues," said Padilla.

By the time she was a sophomore, she was missing school often. Her junior year, she didn't go for a month.

"I would have like these really bad stomachaches or like these really bad headaches," she said.

Eventually Padilla was diagnosed with anxiety and depression.

Child psychologist Lindsay Gerber works at the Mount Sinai Adolescent Health Center. She says they get the most referrals at the start of the school year.

For some children, simply telling them everything will be ok, isn't enough.

"That's sending the message to the kid, 'Ooh, if everything supposed to be OK, it doesn't feel OK, there must be something wrong with me.' And so I always talk about validation," said Gerber.

Acknowledging a child or teen's fears and proactively helping them confront their concerns is a first step. One way to do that is getting back into the school sleep routine a week before school starts. Another is limiting time spent online.

"Don't be on your screens, don't be playing video games, don't be doing all of these things for at least one hour before you go to bed,” says Gerber. "Our brain is taking so much in, and our brain needs some time to calm down."

But for some kids, more intervention is needed. Their invalidated feelings can progress into more complex identity issues.

"Adolescence is all about forming yourself,”"said Gerber. "That's when we see depression, anxiety, when someone is incorporating a lot of negativity and negative self-talk into their identity."

The answer for Padilla was intense therapy and homeschooling.

"Being able to talk one on one with someone, have no judgment, have that support and knowing that someone actually wants to listen to me, that's what helped me," she said.

Padilla graduated high school and is now planning to go to college.