Global sleep dissatisfaction for the assessment of insomnia severity in the general population of Portugal

Background and purpose: This study examines the prevalence and associated factors of insomnia symptoms and sleep dissatisfaction in the general population of Portugal. Patients and methods: We interviewed by telephone 1858 participants aged 18 years or older and representative of the general population of Portugal using the Sleep-EVAL system. Participation rate was 83%. The questionnaire included the assessment of sleep habits, insomnia symptomatology according to DSM-IV and ICSD classifications, associated and sleep/mental disorders and daytime consequences. Results: Insomnia symptoms occurring at least 3 nights per week were reported by 28.1% of the sample and global sleep dissatisfaction (GSD) by 10.1%. Difficulty maintaining sleep was the most frequent symptom (21.0%); 29.4% of subjects with insomnia symptoms reported GSD. Daytime consequences, medical consultations for sleep and use of sleep medication were at least 2 times more frequent among subjects with insomnia symptoms and GSD compared to subjects with insomnia symptoms without GSD; insomnia diagnoses were also more frequent in the GSD group. Conclusions: The results show a severity gradation among subjects with only 1 insomnia symptom, those with 2 or 3 insomnia symptoms but without GSD and those with at least 1 insomnia symptom and GSD. Specific sleep or psychiatric disorders were identified for the majority of GSD subjects (86%); this rate dropped to 50.6% when only 1 insomnia symptom without GSD was reported. GSD appeared to be a good indicator of the presence of a sleep or psychiatric disorder and a good discriminator of the severity of sleep disturbances among subjects with insomnia symptoms. (c) 2005 Elsevier B.V. All rights reserved.