Children’s Temperament and Sleep Behaviors May Be Signs That They Will Become Bullies 

Bullying, which is defined as repetitive, negative actions that are used to deliberately hurt weaker individuals, is a growing problem for many children worldwide (Austin & Joseph, 1996; Olweus, 1993).  Recently, researchers have begun to ask whether certain risk factors in childhood are related to bullying behaviors. One possible risk factor that researchers have begun to examine more closely is temperament.

What is Temperament?

Temperament can be defined as differences between children with regard to levels of emotionality, adaptability, and activity level (Goldsmith & Harman, 1994). One type of temperament that has been found to be related to aggression in past studies is difficult temperament (Rubin et al., 1998). Difficult temperament can be defined as having high levels of negative emotionality (mood) and not adapting well to new or stressful situations. Less research, however, has looked at how different temperamental traits, such as difficultness and activity level, relate specifically to bullying as opposed to general aggression. Therefore, the purpose of this study was to investigate:

  • How temperament measured in early childhood and adolescence is related to observations of relational and physical bullying in preschoolers
  • How temperament measured in early childhood and adolescence is related to reports by adolescents of their own physical and relational bullying.

Results of Our Study on Temperament

The findings from this study showed that early temperament was related to bullying behaviors that children showed during play when they were five years old.

  • Temperament also was related to bullying behaviors that were reported by the same children when they were adolescents.
  • Specifically, children who had high levels of negative mood, activity, and inflexibility at age five showed more relational bullying, such as blackmailing, verbal aggression, and teasing, when they played with an unfamiliar peer when they were five years old.

Adolescents who reported lower levels of activity during the day and higher levels of activity during the night were more likely to have exhibited physical bullying when they were five years old.

  • They also were more likely to report higher levels of both relational and physical bullying in adolescence. 
  • This suggests that there may be a direct link between sleep patterns and bullying behaviors.  It is possible that adolescents who do not sleep well at night are more likely to be under-active during the day, and this dysregulation may increase the likelihood of engaging in negative behaviors such as bullying. 
  • It also is possible that early preschool bullying behaviors may indicate problems that will manifest as later sleep problems in adolescence.

Pay Attention to Childhood Temperament

These findings suggest that it is important to examine temperamental traits, such as difficultness and activity level, when examining the childhood factors that are predictive of bullying behaviors in early childhood and in adolescence. More specifically, these results may help inform prevention and intervention programs because researchers and educators may be able to focus specific interventions on children who are at the greatest risk temperamentally for engaging in bullying activities. Thus, by being able to identify the factors that are associated with later bullying, prevention and intervention programs can be developed and differentiated for children who are at both higher and lower risk for bullying other children.

Pay Attention to Kids’ Sleep Behaviors

In addition, it may be important to pay attention to sleep behaviors of children and adolescents.  Although this study could not prove that sleep problems caused bullying, it did show that the two behaviors are related to each other.  It may be useful for parents to encourage their children to keep regular sleep hours, especially on school nights.  However, it also is possible that children with behaviors such as aggression and bullying may simply be unable to fall asleep at night, and parental persuasion may not be helpful.  The reasons why sleep problems and bullying are related require further research for a more complete understanding of this relationship.


Austin, S., & Joseph, S. (1996). Assessment of bully/victim problems in 8 to 11 year-olds. British Journal of Educational Psychology, 66, 447-456.

DiLalla, L. F. (2002). Preschool social and cognitive behaviors: The Southern Illinois Twins. Twin Research, 5, 468-471.

Goldsmith, H. H., & Harman, C. (1994). Temperament and attachment: Individuals and relationships. Current Directions in Psychological Science, 3, 53-57.

Olweus, D. (1993). Bullying at school. Cambridge, MA: Blackwell.

Rubin, K., Hastings, P., Chen, X., Stewart, S., & McNichol, K. (1998). Intrapersonal and maternal correlates of aggression, conflict, and externalizing problems in toddlers. Child Development, 69, 1614-1629.