Metacognitive beliefs relate specifically to sleep quality in primary insomnia: a pilot study

Objective: To identify whether metacognitive aspects are a specific mental pattern of primary insomnia (PI) or an aspecific correlate of sleep alterations.

Methods: Sleep quality (Pittsburgh Sleep Quality Index: PSQI), anxiety (Self-rating Anxiety State: SAS), depression (Beck Depression Inventory: BDI) and metacognition (Metacognitions Questionnaire - Insomnia: MCQ-I) were evaluated in 24 PI patients, 13 snorers and 17 healthy controls. Rank-transformed PSQI, BDI, SAS and MCQ-I scores were submitted to one-way analysis of variance with group as a between-factor. PSQI was submitted to three-way analysis of covariance (ANCOVA) with MCQ-I, BDI or SAS as covariate and group as a between-factor. Post-hoc analyses were conducted using pairwise comparisons with Sidak correction.

Results: As expected, PSQI scores significantly differentiated the three groups, one from another: PI had highest scores followed by snorers and healthy controls. PI subjects had MCQ-I scores significantly higher than those of snorers and healthy controls; no difference between the latter groups was found. The ANCOVA on PSQI with MCQ-I as a covariate abolished the difference in sleep quality between PI and snorers, whereas covarying for BDI or SAS left the differences in sleep quality between the groups unchanged.

Conclusion: These preliminary results lead to two main conclusions: (i) metacognitive aspects are more prominent in PI when compared to snorers and healthy controls; (ii) MCQI shows higher sensitivity in defining PI patients, with respect to PSQI. If these findings are confirmed and expanded by further studies, the development of a specific metacognitive model of primary insomnia may be warranted.