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Background: In recent years, several GWAS (genome wide association studies) of sleep-related traits have identified a number of SNPs (single nucleotides polymorphism) but their relationships with symptoms of insomnia are not known. The aim of this study was to investigate whether SNPs, previously reported in association with sleep-related phenotypes, are associated with individual symptoms of insomnia., Methods: We selected participants from the HUNT study (Norway) who reported at least one symptom of insomnia consisting of sleep onset, maintenance or early morning awakening difficulties, (cases, N = 2563) compared to participants who presented no symptoms at all (controls, N = 3665). Cases were further divided in seven subgroups according to different combinations of these three symptoms. We used multinomial logistic regressions to test the association among different patterns of symptoms and 59 SNPs identified in past GWAS studies., Results: Although 16 SNPS were significantly associated (p < 0.05) with at least one symptom subgroup, none of the investigated SNPs remained significant after correction for multiple testing using the false discovery rate (FDR) method., Conclusions: SNPs associated with sleep-related traits do not replicate on any pattern of insomnia symptoms after multiple tests correction. However, correction in this case may be overly conservative.

Objectives: This study aim is to compare anxiety levels among individuals experiencing different symptoms of insomnia., Design: Case-control study., Setting: The Nord-Trøndelag Health Study (the HUNT3 study, Norway)., Participants: Of the 50,802 individuals taking part in the HUNT3 study, the current sample comprised 7933 individuals, including 4317 cases with insomnia and 3616 controls., Measurements: Symptoms of anxiety were assessed using Hospital Anxiety and Depression Scale, whereas insomnia symptoms were assessed according to the core Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, nocturnal symptoms. Anxiety levels of the 4317 individuals reporting at least 1 insomnia symptom were compared with the 3616 controls reporting no symptoms. Level of anxiety among participants experiencing combinations of insomnia symptoms was also investigated., Results: Anxiety levels were significantly higher in individuals reporting insomnia symptoms (M = 2.5, SD = 2.4) compared to controls (5.5, SD = 3.7, P < .001). Anxiety levels also differed significantly between different insomnia symptoms (P < .001). Participants reporting all 3 insomnia symptoms had the highest anxiety score (M = 6.8, SD = 4.3), followed in decreasing order by sleep onset insomnia with terminal insomnia (M = 6.7, SD = 4.0), sleep onset insomnia with sleep maintenance insomnia (M = 6.3, SD = 3.8), sleep onset insomnia only (M = 5.8, SD = 3.7), sleep maintenance insomnia with terminal insomnia (M = 5.6, SD = SD = 3.4), terminal insomnia (M = 5.2, SD = 3.4), and sleep maintenance insomnia only (M = 4.5, SD = 3)., Conclusions: Difficulties initiating sleep, both alone and in combination with 1 or 2 of the other symptoms, seem to play a key role in rising anxiety levels., (Copyright © 2019 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.)