Summer has flown by faster than the tide washes away a sand castle, and it’s time for adolescents and teens to head back to school.

The school year may provide parents with some much-needed respite from their stir-crazy children, but it also provides a new wave of concerns, medical and behavioral experts say.

“Just putting those school clothes back on and getting back into the ring can be an adjustment for some kids,” said FOX News contributor Dr. Marc Siegel. “Especially if they’re changing schools or moving from a lower to an upper or middle to an upper school, there can be a period of adjustment.”

Siegel, an internist, suggests parents talk to their children before they head back to class.

“Kids are funny,” he said. “My son’s an introvert, but if you ask him something, he'll tell you. So kids will talk to you if you ask the right way. Don’t assume that just because they’re not saying anything, everything is alright. Ask, because you need to know what’s going on.”

Here are seven concerns parents should address both before and during the school year:

1. The anti-vaccination movement. Misinformation about vaccines being linked to autism has spread like wildfire. As a result, some parents are choosing not to vaccinate their children. The result: diseases that were on the decline, like measles, are once again on the upswing.

“The anti-vaccination movement is based on irrational fears and is absolutely destructive,” Siegel said. “Vaccines are mainly for the sake of the herd, but no one cares about the community. However, if you want to protect the entire population, you have to vaccinate.”

The Centers for Disease Control and Prevention said in July that a measles outbreak had infected at least 127 people in 15 states. It was the largest outbreak since the mid-1990s and most of those infected had not been immunized.

“I can’t say that every kid who doesn’t get vaccinated will get the measles,” Siegel said. “It really depends on where you live. But vaccines are pretty well regulated and drug makers aren’t making a lot of money on them, contrary to popular belief. Getting vaccinated is basically for the public good.”

2. The Internet. Kids are spending more and more time on the Wild Wild Web and it is critical that parents monitor their children’s activity on the computer, said Dr. Keith Ablow, a psychiatrist and FOX News contributor.

“Parents need to know that the Internet can be disinhibiting to young people and adults alike,” he said. “And people do things on the Internet they wouldn’t do in daily life. They offer information they wouldn’t normally offer in an interpersonal interaction that’s more human.”

Ablow recommends parents exert as much parental control as possible over their children’s Internet activities. That means talking to them about what is and isn’t acceptable and monitoring whom they are talking to and what sites they are visiting.

“You literally need to warn them that what they do on the Internet is real,” he said. “I’ve had teenage patients who have sent naked photos or partially naked photos to boyfriends, and if those things get passed around, it can carry a terrible stigma and lead to bullying both in and out of school. Parents need to warn youths that if they do something that’s inappropriate, it places them at risk.”

3. Bullying. Bullying is no longer relegated to the school yard. There are now cyber-bullies lurking on the Internet.

“Bullying is bullying whether it’s done on the Internet or in person and it has significant emotional ramifications,” Ablow said. “So children need to know that they can come to their parents anytime anyone makes them feel unsafe.”

Ablow suggests talking to children when they’re very young and again when they’re older and should stress that being bullied isn’t a sign of weakness or something children and teens should be embarrassed about.

“When somebody is bullied, it often means that they have sensitivities that someone else believes are valuable,” Ablow said.

Parents who are told that their children are being bullied should take immediate action and not assume that it’s just kids being kids or that the school district will handle it.

“The first step is defining the problem, assessing what is happening and going quickly to the student’s teacher and let them know what’s happening,” he said. “Parents need to be the first line of defense and take bullying very seriously. If they have a relationship with the other child’s parents, they may want to reach out in a confidential way.”

Bullying can impact a child’s experiences at school and in life, leading to long-term consequences such as depression and anxiety, Ablow said.

4. Teen and even 'tween sex. From pregnancy pacts to pregnant teen celebrities, many teens are getting the wrong message about sex, and the consequences of that message are the spread of sexually transmitted diseases, including HIV, and a rise in the teen pregnancy rate for the first time in 15 years.

“Sexual behavior between teens and adolescents is more common that most of us appreciated in the past,” Ablow said. “So it’s important for parents to share with their child that self respect involves your body, too, and there are risks to sexual contact.”

Some adolescents use sex as they would a drug, to feel good, said Ablow, and the results can be disastrous.

“You have to give them a twofold message that the risk of pregnancy exists and there’s also the tremendous risk of STDs, including HIV. And this is important because HIV education is one of those things that has receded, yet it’s just as important as ever.”

5. Drug and alcohol use. It’s true that experimentation has long been a rite of passage for teens. However, the age when kids start experimenting continues to decline, and obtaining drugs and alcohol appears to be easier than ever.

“We have very large percentages of kids using drugs or alcohol, and that should be something that every parent is talking to every child about,” Ablow said. “These are pervasive in most towns and cities in America, and kids need to know that you’re relying on them to not break the law at all when it comes to the use of illicit drugs. And yet, it’s so commonplace that young people try these things, you also have to let them know that there will never be a time when you’re not willing to listen when they need to talk.”

Drug and alcohol use can interfere with the maturing process that takes place during the teen years. It also can teach people from a young age to rely on drugs as a means of coping with life, Ablow said.

“What we want is for kids to experience all the varied emotions that go with maturing and feeling competent, and to be able to navigate the choppy waters that go with that,” he said. “And alcohol and drugs don’t make that any easier. Also, we know that violent crime and many indiscretions take place in the presence of alcohol and drugs.”

6. Illness. It was the big story this spring, but Siegel says MRSA may be one of the most over-hyped concerns that parents have.

While it’s true that there is a risk of picking up the so-called staph "superbug" in classrooms, locker rooms and gymnasiums, the spread of the sometimes-fatal bacteria, which is resistant to almost all forms of antibiotics, can be avoided by washing immediately after participating in sports and fitness activities, as sweat is a breeding ground for the germs that spread MRSA.

Parents should worry more about the common cold and other respiratory illnesses, Siegel said.

“Classrooms are swamped with bugs,” he said. “There was an interesting study done in Japan over a 25-year period, during the 1960s to the 1980s. It was done at a time when the flu and other vaccines were mandatory and what they found was that during that period the mortality rate due to the flu was down a million and the rate of respiratory illness were down over 200,000. So that shows you how important vaccines are.”

Avoiding colds and the flu, as well as bacterial infections such as strep throat and MRSA, could be as simple as educating children and teens about the importance of washing hands, Siegel said.

“Getting kids to wash their hands more can be done, but it’s difficult,” he said. “It would require a complete mindset change. So, for now, the best we can do is let schools handle it the way they do and do our best to isolate sick kids.”

7. Childhood obesity. About 23 percent of children in the U.S. are overweight or obese, according to the Centers for Disease Control and Prevention. And with young people increasingly being diagnosed with adult diseases like type 2 diabetes, high blood pressure and high cholesterol, Siegel said this is one problem parents need to be vigilant about.

“It’s an enormous problem because our schools are serving crap,” he said. “How about we put calorie labels on cafeteria food, like we do at Baskin Robbins?”

Siegel said parents should be worried because overweight children are more likely to suffer diabetes, cancer and strokes later in life. Counting calories may not seem to be a kid-friendly task, but Siegel believes that with a little education, it’s doable.

“It depends on how the information is portrayed, but kids can definitely be informed,” he said. “If we had kids meet in the lunch room 10 minutes earlier and gave them a 5-minute lecture, that might work. I know kids go through phases where they’ll only eat French fries. But if you restrict your kids’ choices, then they can’t eat them. Kids will eat when they get hungry no matter what you’re offering them.”