Objectives: Nightmares affect up to 12% of the population and are often comorbid with psychiatric disorders like anxiety and depression. Limited research has examined their influence on nightmare frequency. This study investigates the relationship between depression and trait-anxiety symptoms on incident nightmare frequency at follow-up.
Method: Cross-sectional and longitudinal analyses were conducted on 758 Wisconsin Sleep Cohort participants. Trait anxiety and depression symptom severity were measured using the State Trait Anxiety Inventory and Zung Depression Scale. Ordinal regression determined nightmare frequency cutoffs based on anxiety and depression severity. Cross-sectional associations were assessed with Spearman and Kruskal-Wallis tests. Longitudinal associations were analyzed using adjusted binomial regression of binary nightmare frequency (low: <4/month, high: >5/month) against clinical cutoffs of trait anxiety and depression.
Results: Adjusted models indicated a small correlation between baseline nightmare frequency and trait anxiety (β = 0.01, p = .010) and depression symptoms (β = 0.01, p = .005). High baseline trait-anxiety symptoms were associated with frequent nightmares at follow-up (OR = 3.75, CI95% [1.306,10.793], p < .014), but depression symptoms were not (OR = 1.35, CI95%[0.399, 4.587], p = .627).
Conclusions: Our findings suggest that high trait-anxiety symptoms are associated with increased incident nightmare frequency, when adjusted for depression. However, high depression symptoms were not associated with an increase in nightmare frequency when adjusted for trait-anxiety.