by Diana Divecha, Ph.D

When children are young, it’s easy to celebrate their developmental changes. We write down their first words and send photos of first steps to grandparents; we scaffold their learning by breaking tasks down into manageable parts, and we mitigate their risks. It’s fairly simple. But something breaks down midway on the journey to adulthood. Around about twelve years of age, our children’s behavior can become perplexing to us. It can feel like they just want to push against us, replace us with peers, make bad decisions, and get into trouble. Suddenly, it’s no longer clear to parents exactly what development we’re supporting–and it’s easy to back off, get judgmental, and start reacting. As a result, both parties can feel abandoned.  Fortunately, we have new information to help us understand this period. Scientists are finding that the ages from 12-15 mark perhaps the period of greatest change of any other point in the lifespan. Here’s what happens:

1. Neurons get pruned. The pruning of unused cell bodies in the brain happens throughout the lifespan, but there is especially vigorous pruning from ages 10-14. What does this mean? Because “the neurons that fire together wire together” it means that whatever kids’ brains are doing at that time becomes particularly established. If kids are playing sports, learning music, doing art, those are the connections that will be made. And if they’re lying on the couch watching TV and snacking, those are the connections that will be made. Use it or lose it, brain scientists say.

2. Connections among neurons increase. In early adolescence, the number of connections among brain cells increase, and this integration of wiring continues into emerging adulthood, consolidating (but never ending) around age 25. Thought becomes more integrated and complex, and reasoning and logical thinking improve. This is when kids begin to like to argue–making and testing these new connections and practicing this newfound skill, just as they used to practice dropping things in infancy or toddling about when they first learned to walk.  What can you do as a parent to support this phase? Try to avoid getting caught up in the content of the argument and instead help your child to think and reason well.

3. Different brain systems come online at different times, in particular the limbic system and the prefrontal cortex. The limbic system, in the mid-region of the brain, evolved earlier and runs the feeling circuitry. It is the seat of emotional reactivity–the fight-or-flight system and associations of feelings with situations, experiences, and relationships. As a result, their feelings are more intense and they have higher highs and lower lows.  For teens, part of self-management during this period is understanding the bigger picture.

4. Kids become super sensitive to their social world. This shift makes sense from an evolutionary perspective: in adulthood they’ll need social awareness to go out and form new relationships, bond, mate, coordinate over resources, and create community. This is the age when teens develop an “imaginary audience” and think that people can see them all the time, even inside their head into their thoughts and feelings. They also engage in “impression management,” going to extra lengths to shape themselves to fit in and belong.  Naturally for youth this age, social pain cuts extra-deep. In fact, being excluded lights up more of the pain-processing area of the brain than getting physically bruised does. The upside to this kindness is, kids in middle school can show unmatched kindness to others, generous acts of inclusion, and empathy toward their peers.

5. Dopamine is at an all-time high. Dopamine is the neurotransmitter involved in reward behavior, and it is higher in early adolescence than at any other point in the lifespan. This also makes sense: It takes a lot of energy to leave the nest, and nature has equipped the leavers with feel-good chemistry to take new chances. The downside, though, is that dopamine can seal in behavior with those feel-good experiences, and can be a deadly combination with reward-seeking behavior and substance use/abuse.

6. Peers can undermine decision-making. Young teens get especially dysregulated in the presence of their peers–to the point where their safety can be jeopardized. In a famous study of a video driving simulation, teens who “drove” alone did so about as well as older teens and adults. But when a peer was in the passenger seat, they suddenly made more dangerous decisions and “crashed” more often compared to the others. It gets better, though, and teens gradually become more resistant to peer influence over the course of adolescence until they finally land safely in emerging adulthood, around 20-23.

• As a parent, it’s important to help scaffold your child’s reasoning and decision-making–while remembering that dopamine is surging, and they are super sensitive and emotional. (Translation: tread gently.)

7. Teens need more sleep and need it later on the dial. Teens need about 9.2 hours of sleep per night compared to adults’ 7-8 hours. Their changing circadian rhythms move them about three hours up the clock, and it becomes biologically impossible to go to sleep any earlier. At the same time, though, they need to rise later, and school start times don’t allow that. As a result, most teens are sleep-deprived, with serious consequences. Sleep deprivation is linked to slowed reaction times, impaired recall, disciplinary problems, moodiness, depression, and accidents. In an experiment in the Minneapolis area, when schools started later, students felt less sleepy, got higher grades, had fewer depressive feelings, fewer conflicts, and less bullying–and SAT scores went up.

8. Sexuality. Teens have to cope both with changes in their bodies as well as new feelings of attraction–to and from other people. These new feelings can give rise to inappropriate behavior, objectification of girls, and homophobia, especially for boys. First sexual experiences can also occur at this time. Sadly, a study of 100 women’s first sexual experiences found that only 10% of women had a positive experience the first time, so parents of daughters might want to be particularly conscious about offering guidance. My mantra to my own girls became, “safe sex: emotionally and physically.” Psychiatrist Lynn Ponton’s book, The Sex Lives of Teenagers, is an excellent resource on this topic. [My older daughter, whose background is in sexual health, gives guidance to parents on discussing sexuality here.]

9. Individuation is the process of becoming more independent and autonomous while staying connected to loved ones. Teens often seem to push against parents, but if you look closely, it’s usually over superficial matters, like pop culture. Don’t worry: In close families, kids’ values about important matters generally align with those of their parents over time. Most importantly: Teens want to stay connected to their parents–and have been saying so to researchers for decades. Make sure to cultivate joyful interests, rituals, or hobbies with your teens that keep bringing you back to each other and that balance out the bumpy spots.

Diana Divecha, Ph.D. is a developmental psychologist who writes and speaks about children, teens, and family life. This edited article is reprinted with permission from her website at developmentalscience.com.  Follow her on Twitter @DianaDivecha.