Why are some adolescents more emotionally variable than others?

Adolescence is often associated with changing emotions. A teenager might feel confident and optimistic one day, then discouraged or overwhelmed the next. Some degree of emotional change is a normal part of development, but the amount of change varies considerably between people. While some adolescents experience relatively stable moods, others show much larger shifts from one day to another.

Researchers have identified many factors that may be related to these differences, including stress, social experiences, personality, and self-esteem. But understanding how these factors interact is more complicated than simply identifying whether each one is associated with mood. Stress, for example, may be related to how an adolescent feels about themselves, which could then be connected to how much their emotional state changes over time.

A 2026 study published in Scientific Reports investigated one possible pathway by examining whether perceived stress was associated with fluctuations in self-esteem, and whether those fluctuations were related to greater variability in mood. Instead of asking adolescents to remember how they had generally felt over a long period, the researchers followed them day by day, allowing them to examine changes in self-esteem and mood across a 15-day period.

Stress is partly about how we experience it

The researchers were interested in perceived stress, which refers to how stressful a person experiences their circumstances to be. This is different from simply counting the number of stressful events someone has experienced, because two people can encounter similar situations while experiencing very different levels of stress.

This distinction is particularly relevant during adolescence, when school, friendships, family relationships, changing responsibilities, and other pressures can all contribute to stress. What feels manageable to one teenager may feel overwhelming to another, making the way stress is perceived an important part of understanding its relationship with emotional wellbeing.

The researchers wanted to know whether adolescents who generally perceived more stress also showed greater instability in how they evaluated themselves from day to day.

Self-esteem can fluctuate, too

Self-esteem is a person’s overall evaluation of their own worth. It is easy to think of self-esteem as something relatively fixed, as if someone simply has high or low self-esteem, but people’s evaluations of themselves can change with their experiences. A student might feel capable after doing well on an exam, then question themselves after receiving a disappointing grade. A positive interaction with friends might increase their confidence, while rejection or criticism might temporarily make them feel less secure about themselves.

These changes are referred to as self-esteem fluctuations, and the researchers were interested not simply in whether an adolescent had high or low self-esteem, but in how much their self-esteem changed from one day to the next. Two adolescents could therefore have similar average self-esteem while differing considerably in how stable that self-esteem was across the study.

This distinction gave the researchers a way to investigate whether the stability of self-evaluation might be related to the stability of mood.

Measuring emotions one day at a time

The study included 70 German adolescents who were either 14 or 16 years old. Participants used a smartphone-based assessment system to report their self-esteem and mood once a day for 15 days. Each day, they reported both positive mood, such as feelings of happiness or enthusiasm, and negative mood, such as feelings of distress or sadness.

The researchers then examined how much each person’s responses changed across the study. Rather than focusing only on whether someone generally had high or low self-esteem or mood, they were interested in the amount of day-to-day movement in each measure.

Perceived stress was measured differently. Participants completed a stress questionnaire at the beginning of the study that reflected their broader experience of stress, including stress experienced over the previous year. It therefore provided a measure of general perceived stress rather than a daily measurement of how stressful each individual day had been.

This difference in measurement becomes important when interpreting what the researchers found.

Higher perceived stress was associated with greater self-esteem fluctuation

The first major relationship appeared between perceived stress and self-esteem. Adolescents who reported higher levels of perceived stress tended to show greater fluctuations in self-esteem across the 15-day period.

In other words, adolescents who generally perceived themselves as experiencing more stress also tended to show more movement in how they evaluated themselves from one day to the next. The finding does not establish that stress caused their self-esteem to fluctuate, since the study was observational, but it suggested that perceived stress and instability in self-evaluation may be connected.

That relationship provided one possible explanation for how stress could be related to emotional variability. If adolescents who perceive more stress also experience greater changes in how they view themselves, changes in self-evaluation could potentially be connected to changes in mood as well.

Greater self-esteem fluctuation was associated with greater mood variability

The researchers next examined whether fluctuations in self-esteem were related to fluctuations in mood. They found that adolescents whose self-esteem changed more from day to day also tended to show greater variability in both positive and negative mood.

The finding was not simply that lower self-esteem was associated with worse mood. Instead, it concerned variability. An adolescent could have relatively low self-esteem while maintaining a fairly stable emotional state, just as someone with relatively positive self-esteem could experience substantial changes in mood. What distinguished the adolescents in this analysis was how much their self-evaluation and emotional state moved over time.

This suggests that the stability of self-esteem may be relevant to the stability of mood. Adolescents whose evaluations of themselves fluctuate more may also experience greater changes in their emotional states, although the study cannot determine whether changes in self-esteem actually produce changes in mood.

Could self-esteem connect stress and mood?

The researchers then brought the two relationships together. If higher perceived stress was associated with greater self-esteem fluctuation, and greater self-esteem fluctuation was associated with greater mood variability, they wanted to know whether self-esteem fluctuation could statistically account for part of the relationship between perceived stress and mood variability.

They tested this using a mediation analysis, a statistical method used to examine whether one variable helps explain the relationship between two others. The analysis found significant indirect relationships between perceived stress and both positive and negative mood variability through self-esteem fluctuation.

The overall pattern can therefore be described as higher perceived stress → greater self-esteem fluctuation → greater mood variability. However, the arrows in this pathway should not be interpreted as proof that one factor causes the next. The study found a pattern of associations that is consistent with this pathway, rather than experimentally demonstrating that stress causes self-esteem to fluctuate and that those fluctuations then cause changes in mood.

That distinction is especially important when studying something as complex as adolescent emotional development, where many variables can influence one another at the same time.

The timing of the measurements matters

There is another limitation built into the way the study was designed. Self-esteem and mood were measured every day for 15 days, but perceived stress was measured only once, at the beginning. The researchers could therefore observe day-to-day changes in self-esteem and mood, but they could not determine whether an adolescent’s stress level rose and fell alongside those changes.

For example, the study cannot tell us whether a particularly stressful day was followed by a change in self-esteem and then a change in mood. To examine that possibility, researchers would need to measure perceived stress repeatedly throughout the study rather than relying on a single baseline assessment.

Instead, the study shows that adolescents who generally perceived more stress tended to have greater self-esteem variability during the subsequent daily assessments, and that greater self-esteem variability was associated with greater mood variability. The distinction may seem subtle, but it determines what the researchers can legitimately conclude about the direction of the relationships.

What does this tell us about adolescent emotions?

The findings offer one possible explanation for why emotional variability differs between adolescents. Stress may be part of the picture, but the relationship between stress and mood may involve how stable a person’s self-evaluation is across their experiences.

This does not mean that self-esteem fluctuation is the single explanation for changing moods during adolescence. Emotional variability can be influenced by many factors, including social experiences, relationships, personality, sleep, and the broader environment. Nor does the study suggest that emotional fluctuation itself is inherently abnormal, since some degree of change is expected during adolescence.

Instead, the study points toward a more specific way of thinking about individual differences in emotional stability. Rather than asking only whether an adolescent feels stressed or whether they generally have high or low self-esteem, researchers can also ask how consistently they evaluate themselves over time and whether that stability is connected to the stability of their emotions.

A more dynamic view of adolescent mood

It is tempting to describe adolescent mood changes simply as the result of stress, hormones, or the general turbulence of growing up. This study suggests a more complicated picture in which the relationship between stress and emotion may involve changes in how adolescents see themselves.

Adolescents who perceived more stress tended to show greater fluctuations in self-esteem, while those greater fluctuations were associated with greater variability in both positive and negative mood. The study cannot establish that this is a causal chain, but it identifies a relationship that may be important for understanding why some young people experience more emotional variability than others.

Future research will need to follow larger groups of adolescents for longer periods and measure stress, self-esteem, and mood repeatedly. That would allow researchers to examine whether changes in stress actually precede changes in self-evaluation and whether those changes are then followed by changes in mood.

For now, the study adds another piece to the puzzle of adolescent emotional development: how we feel about ourselves may not only matter because of whether that evaluation is positive or negative, but also because of how much it changes over time.

Based on Borzikowsky, C., Prignitz, M., Guldner, S. et al. “A longitudinal daily diary study of stress, self-esteem fluctuation, and mood variability in adolescents.” Scientific Reports 16, 24148 (2026).