Personality profiles in paradoxical insomnia: a case-control study.

Introduction: Paradoxical insomnia (PARA-I) is a clinically challenging condition to diagnose and treat. Previous findings suggest that personality profiles of patients with PARA-I may be different from other subtypes of insomnia. Therefore, investigation of these profiles can be helpful in the clinical management of these patients.

Objective: The current study compares personality profiles of individuals with paradoxical insomnia (PARA-I), psycho-physiological insomnia (PSY-I), and normal sleepers (NS).

Material and Methods: A cross-sectional case-control study was conducted in the Sleep Disorders Research Center of Kermanshah University of Medical Sciences, Kermanshah, Iran between 2015 and 2017. Patients with PARA-I (n=20), PSY-I (n=20), and NS (n=60) were matched for age, gender, education, and history of mental and/or physical illness and completed the Minnesota Multiphasic Personality Inventory (MMPI) short form. One-way analysis of variance (ANOVA) and the Kruskal-Wallis test were used to compare subscale means across groups.

Results: With the exception of the schizophrenia scale (P =.059), significant differences were found in all subscales of the insomnia groups compared to the NS group (P=.001). Compared to the NS group, patients with PARA-I showed significant differences in the hysteria and hypomania subscales (P<.05) and patients with PSY-I showed significant differences in the hysteria, hypochondriasis, and psychopathic subscales (P=.001). No significant differences were found between the PARA-I and PSY-I groups on any subscale.

Conclusion: This study demonstrates that significant differences in the personality profiles on the MMPI exist between PARA-I and PSY-I patients compared to NS. These findings should inform the diagnosis and future treatment approaches for insomnia.