New research suggests that teen mood swings decline gradually as they get older.

Researchers from VU University Amsterdam, the EMGO Institute for Health and Care Research, Utrecht University, and Tilburg University said the findings should reassure parents about their moody teens while also helping identify when instability is considered risky and requires intervention.

"We found that early adolescence is the period of the greatest volatility, but adolescents gradually stabilize in their moods," Hans M. Koot, a coauthor of the study, said in a statement. "An important message to teens, parents, and teachers is that temporary mood swings during early adolescence might actually be normal and aren't necessarily a reason to worry."

For the study, researchers followed nearly 500 middle- to high-income Dutch adolescents between the ages 13 and 18. Of the participants, 40 percent were at high risk for externalizing behaviors (e.g., aggressive or delinquent behavior) at age 12. Using Internet diaries, the teens rated their daily moods in terms of happiness, anger, sadness, and anxiety during three weeks of the school year for five years.

The researchers believe that adolescents' mood swings could become more stable because events that are new in early adolescence -- such as first romances and conflicts with parents about leisure time -- happen less frequently as teens grow older. And it's likely that adolescents figure out over time how to deal more effectively with changes in their moods.

"In general, heightened mood variability will eventually pass," Dominique F. Maciejewski, first author of the study, said in a statement. "By demonstrating that most teens get less moody across adolescence, our study provides a solid basis for identifying adolescents who develop in a deviant way. In particular, teens who continue to be extremely moody or who get even moodier across adolescence may need to be monitored more closely since earlier studies have shown that extreme mood swings are related to more emotional, behavioral, and interpersonal problems."

The findings are detailed in the journal Child Development.