Is head-banging normal behavior, or not? What about constant motion, or a fear of strangers or new situations? As the rate of diagnosis for children’s health conditions, such as ADHD, autism and sensory processing disorder has increased, more and more parents are wondering which behaviors are red flags, and which are completely normal. The normal-or-not question doesn’t have any easy or obvious answers though. That’s because the range of “normal” behavior and development can vary greatly, and depends on a child’s age, health, history and environment. Here are six common behaviors that can be normal—or not. Anxiety Normal: Separation anxiety—fear of strangers, and distress at being separated from a caregiver—is completely normal from the second half a baby’s first year until well into the preschool years. Childhood fears such as fear of the dark are also incredibly common. Physical manifestations of anxiety, such as fidgeting or hair twirling, are normal too. And while it might look alarming, rhythmic rocking and rolling—even to the point of banging into walls—can be normal. Some children soothe themselves to sleep this way. Not Normal: Anxiety crosses the line into “not normal” when it interferes with a child’s functioning. Children who continue to have strong separation anxiety after the age of four, for instance, may resist going to school or leaving the house; in this case, their anxiety interferes with their growth and development. Panic attacks, which can manifest as intense fearfulness, trembling, a racing heartbeat and difficulty breathing, aren’t normal, but they are common. Treatment can help. Hair pulling that causes hair loss is called trichotillomania, affects as many as 1 in 100 children. Experts believe trichotillomania is related to anxiety. Mood Swings Normal: Teenagers are known for their mood swings. So are toddlers! And children, like all human beings, experience variations in emotion. It’s perfectly normal to be sad after a friend moves away, for instance, or following the death of a grandparent. Not Normal: Sudden or striking mood swings—from very high to very low—can be a symptom of bipolar disorder. In kids with bipolar disorder, mood swings are extreme and accompanied by changes in sleep patterns, energy level and thinking. Experts say as many as one-third of children who have been diagnosed with depression may actually have bipolar disorder. Temper Tantrums Normal: According to the American Academy of Pediatrics, temper tantrums are common between ages 1 and 4. Children this age want immediate gratification, and get frustrated when their desires aren’t met. Temper tantrums are a normal expression of frustration in toddlers and preschoolers who haven’t yet developed strong language skills and self-control. Not Normal: Tantrums that persist after the age of four can be a sign of trouble. In fact, frequent tantrums in preschoolers may also warrant evaluation. While almost all preschoolers (84%, according to one study) experience tantrums, only about 9% have daily outbursts. Experts recommend seeking professional evaluation if your child’s tantrums are frequent, intense, cause injuries or property destruction, or are accompanied by other troubling symptoms, such as nightmares or clinging. Inattention and Impulsivity Normal: Toddlers have notoriously short attention spans. So do teenagers who aren’t interested in the topic at hand. And impulsive behavior—such as leaping from the top of a play structure to the ground, or blurting out answers—is common in childhood, especially among boys. Not Normal: The line between normal and abnormal levels of attention, activity and impulsivity is a fine one, and influenced by environment and culture. Experts begin to consider a diagnosis of attention deficit hyperactivity disorder (ADHD) when a child’s inattention, activity and impulsiveness are more extreme than would be expected for a child of that age, and when those behaviors cause problems at home and at school. Potential red flags include constant motion (with no apparent purpose), disruptive behavior, and difficulty completing tasks. Aggression Normal: Biting and hitting are completely normal behaviors for children between the ages of 1 and 3. And fighting—both physically and verbally—is common throughout childhood. But as children grow and develop self-control, verbal skills, and problem-solving abilities, such outbursts usually decrease. Not Normal: Frequent or severe aggressive behavior can be a cry for help or a sign of a mental health condition. Seek professional evaluation if your child is cruel to other people or animals, damages property, or frequently starts fights. If your child is exhibiting any behaviors that are concerning to you, talk to your healthcare provider. Your provider can rule out medical causes, conduct an evaluation, and refer you to an appropriate expert for help, if necessary.