The Relation between Insomnia Symptoms, Mood, and Rumination about Insomnia Symptoms

Study objectives: Research suggests that rumination may play an important role in insomnia. Whereas some have suggested that rumination mainly relates to depression, the evidence suggests that there may be insomnia-specific rumination. This paper explores insomnia symptom rumination across two distinct samples of varying levels of depressed mood and insomnia symptom severity. Methods: The first sample consisted of nonclinical participants (N = 327) with a range of insomnia and depressed mood symptoms, and the second sample consisted of those who met both Major Depressive Disorder and Insomnia diagnoses (N = 66). Rather than relying on a measure developed for those with depression, we developed and tested an insomnia-specific measurement scale based on items from previous rumination studies and the addition of items derived from common daytime insomnia symptoms. Results: Internal consistency was highly acceptable across the two samples for the new insomnia-specific rumination measure (Cronbach alpha was 0.93 and 0.94). In the first study, poor sleepers reported significantly higher levels of daytime symptom rumination than did good sleepers. Across both studies, rumination about daytime insomnia symptoms and depression were significantly correlated; however, insomnia rumination scores predicted insomnia even after controlling for depression. Moreover, in Study 2, insomnia-specific rumination was related to insomnia, but general depressive rumination was not predictive of insomnia. Conclusions: The findings provide support for the use of this insomnia-specific rumination scale; moreover the findings support previous observances regarding rumination about daytime insomnia symptoms that are not exclusive to depression.