Nearly 9 out of every 10 teenagers in the U.S. report that their classmates drink, smoke or use drugs in school, according to National Survey of American Attitudes on Substance Abuse XVII: Teens.

The survey found that more than half of school students know at least one person on campus that are into illicit drugs like ecstasy, cocaine, meth or heroin and a place where they could get drugs during school. Teenagers have easy access to drugs and can get prescription drugs in as little as one hour.

It is estimated that 1 out of every 5 teens, or about 17 percent, uses drug, drink or smoke. More than 50 percent teenagers attending private schools said that their school was drug-infected. This is a rise from 36 percent teenagers last year.

"For millions of American teens, drugs and alcohol, not more advanced education, are what put the 'high' in the high schools they attend. For millions of parents trying to raise drug-free kids, the 'high' school years are the most dangerous times their children face, and the 'high' schools are a dangerous place to send their kids," said Joseph A. Califano, Jr. Founder and Chairman Emeritus of CASAColumbia and former US Secretary of Health, Education, and Welfare.

Party Pictures on Facebook, Twitter and Tumblr

The peer pressure has now extended to digital world. According to the report, nearly 75 percent of children between the ages of 12 and 17 have seen pictures of other teens using drugs, drinking or smoking at a party and having fun. Teenagers who have seen these pictures on social networking sites like Facebook, Twitter or Tumblr are four times as likely to use marijuana and almost three times more likely to have used alcohol or tobacco than teenagers who haven't seen such pictures.

"This year's survey reveals a new kind of potent peer pressure-digital peer pressure. Digital peer pressure moves beyond a child's friends and the kids they hang out with. It invades the home and a child's bedroom via the Internet. So parents should be aware of what their children are viewing on social networking sites. If their teens are seeing pictures of other teens partying with marijuana and alcohol, getting drunk or passed out, or using drugs, they may think it looks like fun and want to try it," said Califano.

The survey also found that children who are home alone all night are more likely to drink or smoke pot. Compared to teens that were never left alone overnight, those who stayed at home all night without a guardian were twice as likely to use alcohol or marijuana and about three times more likely to have used tobacco.

Another important factor in deciding whether or not a teenager uses drugs or drinks alcohol is parental approval. Strong parental disapproval towards substance use resulted in the reduced likelihood of teenagers wanting to use these substances.