Think about a day when small interruptions feel unusually frustrating and patience is harder to find. What might that change in irritability tell us about how you are functioning that day?
These questions shaped our study, recently published in Scientific Reports. We examined irritability in college-attending young adults, asking how a person's general tendency toward irritability relates to their changing experiences and to daily physical and mental functioning.
The question behind the study
This paper grew out of my doctoral dissertation research at the University of California, Irvine, with co-authors Miriam Bender, Sarah R. Martin, and Michelle A. Fortier. Much of the existing research on irritability has focused on children and adolescents. We wanted to understand its expression in young adulthood, when academic demands and other everyday pressures provide an important context for emotional experiences.
We focused on two dimensions. Trait irritability describes a relatively stable tendency to become irritated. State irritability describes experiences that fluctuate over time. Studying both allowed us to ask whether they carried different information about functioning.
Following irritability through daily life
To capture those fluctuations, we used ecological momentary assessment in which repeated surveys completed during participants' everyday lives. Following a baseline assessment, students received morning and evening surveys for 14 consecutive days. They reported irritability, perceived stress, and positive and negative emotions. Evening surveys also assessed physical and mental functioning.
The schedule balanced repeated observation with feasibility for college students. It also let us examine whether morning experiences were associated with functioning reported that evening. Our primary statistical models included 88 students aged 18 to 25.
An important design choice concerned the time frame of the questions. We adapted their usual retrospective wording to capture experiences during the current day. This brought the measurements closer to daily life, although the findings still depend on participants' self-reports.
Understanding change within each person
The analytical challenge was to separate differences between people from changes within the same person. Comparing a student who is usually more irritable with one who is usually less irritable answers a different question from asking what happens when a particular student feels more irritable than usual.
Our models kept those questions separate. Each person's own average provided a reference for their daily fluctuations. Nearly half of the observed variation in state irritability occurred within individuals over time. That finding helps explain why a single assessment cannot fully describe the patterns we were studying.
Different patterns for physical and mental functioning
Higher trait irritability was associated with poorer self-reported physical functioning. Its association with mental functioning was not statistically significant in our models. This does not establish that trait irritability is unrelated to mental health; it describes the result for the functioning measure and sample we studied.
State irritability showed a different pattern. When students reported more irritability than was usual for them, they also reported poorer mental functioning. The corresponding association with physical functioning was smaller. These associations were examined alongside perceived stress and positive and negative emotions.
The morning-to-evening analyses added a useful perspective. Greater-than-usual morning irritability was associated with poorer mental functioning that evening. Morning state irritability did not show a statistically significant association with evening physical functioning. The timing helps us examine how experiences relate across the day, but these observational findings do not show that irritability caused later difficulties.
Stress and positive emotions are part of the picture
Students reported greater state irritability when they felt more stressed or experienced more negative emotions than usual. Students with higher average stress or negative emotions also reported greater state irritability. Accounting for these factors substantially weakened the association between trait and state irritability, showing how much context contributes to the overall picture.
We also tested whether a person's average stress level changed the strength of the trait-state relationship. The study did not find statistically significant evidence for that interaction. Stress was associated with irritability, but a claim that it amplified trait vulnerability would go beyond our results.
Positive emotions were associated with better physical and mental functioning, both in the concurrent analyses and when morning reports were related to evening functioning. This raises useful questions about emotional resources in daily life. It does not demonstrate that increasing positive emotions would improve functioning.
Where this work leads
For researchers and professionals supporting young adults, the findings encourage attention to when irritability occurs and how it varies alongside stress and daily functioning. The functioning scores reflect self-reported health-related quality of life; they are not diagnoses of depression or anxiety.
Our sample came from one university and was predominantly female. Two weeks of observation cannot establish long-term patterns, and the results need replication in larger, more diverse groups. Longer studies could examine reciprocal relationships and the role of emotion regulation, while objective measures could add information beyond self-report.
The question I hope this paper encourages is how we can understand a young adult's irritability in the context of their own daily life. Following those changes may help us identify when emotional difficulties coincide with problems in functioning and which questions future research should pursue.
I am grateful to the students who participated and to the collaborators and mentors who supported this study project.
Read the paper: Trait and state irritability in young adults