Not all task-unrelated thoughts (TUT) are created equal - TUT characteristics as predictors of affective states and heart-rate variability.

Task-Unrelated Thoughts (TUT) are a prevalent transdiagnostic phenomenon, robustly associated with both adaptive and maladaptive outcomes. However, it is still not clear which factors determine the maladaptive outcomes of TUT. In this study, we focused on analysing the role of a wide spectrum of TUT characteristics in everyday functioning, specifically their associations with momentary affective states, depressive symptoms, heart rate variability, and sleep quality. Forty-seven participants took part in a seven-day ecological momentary protocol, completing momentary and daily questionnaires alongside continuous ECG monitoring. Additionally, trait-level measures of mind-wandering, repetitive negative thinking, and depressive and anxiety symptoms were collected using self-report questionnaires. The results show that TUT Emotional Appraisal—especially perceived burden and thought valence—were significant predictors of affective momentary outcomes. In contrast, perceived usefulness of TUT significantly predicted depressive symptoms at the daily level. Part of the associations between TUT characteristics and outcomes was moderated by individual differences, such as tendency to engage in mind-wandering or repetitive negative thinking, as well as trait-level depressive and anxiety symptoms.