Sudden Changes in Behavior in Teens

The changes in your child during the teen years can pack a powerful punch. While the physical differences quickly catch your attention, the difference in her attitude and behavior may seem more drastic. One day she’s playing with dolls and the next she’s playing with makeup. Some changes are normal, while others can indicate an underlying issue.

Normal Teen Behavior

As a teen develops physically, his cognitive and social skills do as well. The changes that occur in the brain give a teen the ability to reason, develop philosophies and a sense of justice, think abstractly, establish meaningful relationships and question values. While such changes may sound innocent, they translate into the exercising of argumentative skills, risk-taking behaviors, self-centeredness and identity development, according to the University of Maryland Medical Center’s online article, “Adolescent Development—Overview.” During this time of change, it’s normal for a teen be moody, test boundaries, act impatiently, value friends over family and be secretive 2. Lehman states that such behaviors are a teen’s way of developing independence and his own identity.

Substance Abuse

Substance abuse can have a dramatic impact on your teen’s behavior. It’s not unusual for a parent to say that a teen’s behavior seemed to change overnight because of drug and/or alcohol use. According to Lehman, when a teen has a substance abuse problem, drugs or alcohol become an increasingly important part of her life. As the dependence grows, a teen’s behaviors begin to seem more unusual. The Mayo Clinic states in its article, "Teen Drug Abuse: Help Your Teen Avoid Drugs,” that teens with an addiction may suddenly lose interest in friends or activities, experience a decline school performance, sleep too little or too much and/or have a change in appetite 3. A teen may become secretive about where she’s going or who she’s going to visit. In addition to acting more hostile, a teen battling an addiction may also suddenly have an unexplained need for money. Professional treatment is critical to helping a teen with an addiction.


Bouts with the blues and sadness can come and go during the teen years as hormones take their toll, but changes in behavior that last at least two weeks may be signs of depression. The article “Adolescent Depression—Symptoms” by the University of Maryland Medical Center indicates that a teen who feels depressed tends to view everything in a negative light 2. Teens may communicate and experience depression differently than adults, and some of the first signs can include a lack of interest in past hobbies and excessive moodiness or crying. A teen’s sleeping and/or eating patterns may change, and he may want to spend more time than usual alone. In addition to feeling tired a lot, a depressed teen may express negative feelings about his self-worth. Taking a teen’s feelings seriously and access to mental health services are essential to helping a teen overcome depression.

Bullying or Abuse

When a teen is the victim of bullying or abuse, she may become instantly withdrawn from everyone. It’s common for a teen to not want to go to the places where she knows her abuser or bully is, like school, and make excuses for not going. A victim of abuse or bullying may have increased nightmares or difficulty sleeping for no reason, and may express that she deserves to have bad things happen to her. A youth who is bullied or abused may feel embarrassed and not tell her parents or trusted adults about it, but she may drop clues by indicating that she wants to have a conversation about issue related to the abuse she’s experiencing.