Insomnia and risk of chronic musculoskeletal complaints: longitudinal data from the HUNT study, Norway.

BACKGROUND: The aim of this study was to investigate the prospective association between insomnia and risk of chronic musculoskeletal complaints (CMSC) and chronic widespread musculoskeletal complaints (CWMSC). A second aim was to evaluate the association between insomnia and number of body regions with CMSC at follow-up. METHODS: We used data from the second (HUNT2, 1995-1997) and third (HUNT3, 2006-2008) wave of the Nord-Trøndelag Health Study (the HUNT Study). The population-at-risk included 13,429 people aged 20-70 years who reported no CMSC at baseline in HUNT2 and who answered the questionnaires on insomnia in HUNT2 and CMSC in HUNT3. Insomnia was defined according to the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) with minor modification, whereas CMSC was assessed for nine different body regions. CWMSC was defined according to the 1990 criteria by the American College of Rheumatology. We used Poisson regression to estimate adjusted risk ratios (RRs) for CMSC and CWMSC at 11 years follow-up. Precision of the estimates was assessed by a 95% confidence interval (CIs). RESULTS: Insomnia at baseline was associated with increased risk of any CMSC (RR 1.16, 95% CI 1.03-1.32) and CWMSC (RR 1.58, 95% CI 1.26-1.98) at follow-up. RR for CMSC for specific body regions ranged from 1.34 (95% CI 1.05-1.73) for the knees and 1.34 (1.10-1.63) for the neck to 1.60 (95% CI 1.19-2.14) for the ankles/ft. Further, insomnia was associated with increased risk of CMSC in 3-4 regions (RR 1.36, 95% CI 1.05-1.77), and 5 or more regions (RR 1.93, 95% CI 1.40-2.66), but not 1-2 regions (RR 0.99, 95% CI 0.80-1.24). CONCLUSIONS: Insomnia is associated with increased risk of CMSC, CWMSC, and CMSC located in 3 or more body regions.

Headache and insomnia in population-based epidemiological studies.

BACKGROUND: Several epidemiological studies on the association between primary headaches and insomnia have been published in recent years. Both disorders are frequent, and our purpose was to review results from population-based studies exploring this association. METHODS: We performed a literature search in PubMed for "insomnia" (or sleep disturbance) and "headache" (or migraine) linked with "epidemiology." Two hundred and eight records were identified. Three longitudinal and 10 cross-sectional studies met our inclusion criteria: population-based design with at least 200 participants including a numerical estimate of the association between headache and insomnia. RESULTS AND CONCLUSIONS: In nearly all studies, primary headaches, including migraine and tension-type headache, were significantly related to insomnia symptoms with OR estimates ranging from 1.4 to 1.7. The odds were even greater, from 2.0 to 2.6, for frequent, comorbid or severe headache. Recent large longitudinal studies from Norway found a bidirectional, possibly causal, association between headache and insomnia. However, not all studies used standardized diagnostic criteria for either headache or insomnia. Further research should use well defined and validated diagnostic criteria both for insomnia and headache types in order to improve the comparability between studies, investigate causality and clarify the relevance of the findings for clinical practice.

The relationship between obstructive sleep apnea and insomnia: a population-based cross-sectional polysomnographic study.

BACKGROUND: The relationship between insomnia and objectively measured obstructive sleep apnea (OSA) severity has not previously been investigated in both genders in the general population. The main aim of this population-based polysomnography (PSG) study was to evaluate the cross-sectional association between severity of OSA and DSM-V insomnia and insomnia severity. METHODS: A random sample of 1200 participants in the third Nord-Trøndelag Health Study (HUNT3) was invited and 213 (18%) aged between 21 and 82 years underwent an ambulatory PSG, a semi-structured interview, and a sleep-specific questionnaire. A proxy DSM-V insomnia diagnosis as well as an Insomnia Symptom Score (ISS, range 0-12) were calculated from three insomnia questions and one daytime sleepiness symptom question. Participants were then divided into three groups according to their apnea-hypopnea index (AHI): AHI < 5 (without OSA), AHI 5-14.9 (mild OSA), and AHI ≥ 15 (moderate-to-severe OSA). Associations between prevalence of insomnia and OSA groups were assessed by logistic regression models adjusted for age and gender. Associations between ISS and OSA were assessed in a general linear model with contrasts. RESULTS: A total of 25.2% (29.1% women, 12.5% men) had insomnia. Insomnia prevalence did not differ between subjects with and without OSA, but ISS differed significantly between OSA categories (ANCOVA df 2, F = 6.73, p = 0.001). ISS was lower in the moderate-to-severe OSA-group compared to those without OSA (mean difference -2.68; 95% [CI -4.33, -1.04]; p = 0.002). In subjects with moderate-to-severe OSA, ISS correlated negatively with age (Pearson r = -0.66, p = 0.015). CONCLUSION: In this population-based PSG study, no overall statistical association between OSA and insomnia prevalence was found. However, participants with moderate-to-severe OSA reported less insomnia symptoms than subjects without OSA, in particular in older individuals.