JUDY WOODRUFF: Back in this country, we turn to a classroom program designed to help young people cope with PTSD, a condition caused not by the shock of war, but by the stresses they encounter in life outside their schools.

MAN:We go — we start with our mountain pose, OK? And as you breath out, lean to the right and feel that stretch along your left side.

JEFFREY BROWN:At Cesar Chavez Academy in East Palo Alto, California, these seventh graders are part of an experiment to see if focused breathing can lead to focused learning.

MAN: And as you breathe out, come back to the middle.

JEFFREY BROWN:Stanford University researchers John Rettger and Michael Fu are using yoga and what is known as mindfulness practices to help students concentrate on class work.

MAN:These practices are really designed to help us feel a little bit more awake, aware and also relaxed.

MAN:We're going to get into sort of our relaxed state, and we're going to get into mindful practice. So, first of all, for mountain pose, everybody, go ahead and move your feet so that they are shoulder-width apart. And let's take three breaths together. Let's inhale and exhale.

JEFFREY BROWN:Cesar Chavez is in a low-income, high-crime neighborhood, and many of these students face real-world stresses, anxieties and fears, which can impair their ability to learn.

AMIKA GUILLAUME, principal, Cesar Chavez Academy: We have, by the 2010 census, as many as 50 percent of students who are homeless.

There are some very concrete things, like a telephone, a mattress, a refrigerator with food in it, an address that you are in charge — when I say children are under stress and duress, it's the little things. Let's not to mention the shootings. Let's not even go into the gang war in our neighborhoods. Just the little, simple things are very stressful.

MAN:I want you to notice inward what you are feeling, so an emotion. And then I want to have somebody volunteer what their emotion is.

STUDENT:Relaxed.

MAN: Relaxed? Good.

JEFFREY BROWN: Dr. Victor Carrion, a professor at Stanford University's School of Medicine and head of Early Life Stress Research Program, oversees the project at Cesar Chavez Academy.

DR. VICTOR CARRION, Stanford University School of Medicine:We talk about adverse childhood experiences. We talk about trauma. Here, we have the words suicide, drugs, sexual abuse, starving. This is what adverse childhood experiences are. This is the constant life of these children on a day-to-day basis. And not only do they live it, but they have reminders in their own school.

JEFFREY BROWN: Carrion and his colleagues are trying to understand how children respond to daily stress, emotionally and even physiologically.

DR. VICTOR CARRION:With functional imaging, we actually can see what the brain is doing.

JEFFREY BROWN:He showed us brain images of children who suffer from chronic press, revealing evidence of both cognitive impairment and post-traumatic stress disorder, or PTSD.

This link between stress and behavior actually shows up in the brain?

DR. VICTOR CARRION: It does.

JEFFREY BROWN:And, so, when there is stress or trauma in somebody's life, it shows up there?

DR. VICTOR CARRION:Well, yes, what we can see is there is a deficit in the area of the middle frontal cortex in kids that have PTSD.

JEFFREY BROWN: And in the developing brain of a child, Carrion says, PTSD can discourage learning.

DR. VICTOR CARRION: So the issue that we have with stress and chronic stress, and when it manifests as a PTSD syndrome or disorder is that some of the areas that are affected are areas that we need for our learning. For example, brain centers that process memory, brain centers that process executive function are particularly vulnerable. So PTSD can have an effect in how children learn.

JEFFREY BROWN: According to Carrion, up to 30 percent of children who live in low-income, high-crime neighborhoods will show symptoms of PTSD.

AMIKA GUILLAUME:Do I think that stress of our community can get to a child? One hundred and ten percent, absolutely. For every child who acts out at our school, I can look exactly to the point in their life where things are not working. Every single time, there is a very concrete, very sad story about why this child is not getting what he or she needs.

MAN:Bring your arms up, and then put your left leg right around your knee.

JEFFREY BROWN: By teaching children to pay close attention to their breathing and movements, Stanford medical student Michael Fu hopes they will better prepared to concentrate.

MICHAEL FU, Stanford University medical student:The principals of mindfulness really try to make you focus on the present moment. So whether or not you came in this morning experiencing something stressful at home or something bad happened, for you to be able to come into the classroom and really embrace it and embrace the learning, I think it really allows students to reach their potential.

JEFFREY BROWN:The Stanford team is also encouraging students to use these practices beyond the classroom.

MAN: This is then a tool that is available to us. So if we're working with some challenging emotions like anger or some fear or some sadness, these are things we can do to help change how we're feeling, right, and we can feel a little bit better.

JEFFREY BROWN:These students were just finishing a 10-week program when we visited. Teacher Marquel Coats said that, at first, there was plenty of skepticism.

MARQUEL COATS, teacher: It took us out of our comfort zone to be like moving our bodies and breathing in and out in front of everyone without giggling and things like that. Once you just kind of just get in the zone on your own, you become comfortable, and it becomes something natural, as opposed to something that you're nervous about.

JEFFREY BROWN:Brayan Solorio, says that he uses both mindfulness and yoga at home when his mother, who works her third job at night, refuses to let Brian play outside.

BRAYAN SOLORIO, student:When I get home, I want to play, but she doesn't let me because it's too dark now. And I get so mad. And then I put my yoga mat that they give me, and I start using it. The difference is that I'm angry, and then as soon as I use it, I'm not angry no more. It calms me down.

JEFFREY BROWN:Can children learn to live with trauma? Do they learn to cope?

DR. VICTOR CARRION:They learn to cope if we teach them. If we don't do anything, their PTSD is not going to go away. So, by adolescence, for example, individuals may develop self-injurious behaviors or they may develop substance abuse as a way of self-medicating. So, if PTSD, if not addressed, is avoided, is just going to get worse.

JEFFREY BROWN: Teacher Marquel Coats says she has seen positive results.

MARQUEL COATS: I have seen tremendous, like, growth in students from being in mindfulness, from, like, kids that have attitudes are quick to get upset about something, breathing and taking it slower, and then saying, you know, I didn't like that or please don't do that, as opposed to lashing out.

JEFFREY BROWN:For Principal Amika Guillaume, all of this is very personal. Her sister was murdered when, as a teenager, she got caught up in a fight. Guillaume today says keeping emotions in check can keep children safe.

AMIKA GUILLAUME:If we can get kids to the point that they realize that, oh, I'm getting hotheaded, oh, my adrenaline is flowing, I am not thinking clearly, I need to stop, step back and reassess, then maybe we have a chance.

MARQUEL COATS:And this last week, how often did you play with your friends, never, a little, sometimes?

JEFFREY BROWN:The Stanford team is now gathering data from students about the effectiveness of the mindfulness program.