Differences in anxiety levels among symptoms of insomnia. The HUNT study

Abstract

ObjectivesThis study aim is to compare anxiety levels among individuals experiencing different symptoms of insomnia. DesignCase-control study. SettingThe Nord-Trøndelag Health Study (the HUNT3 study, Norway). ParticipantsOf the 50,802 individuals taking part in the HUNT3 study, the current sample comprised 7933 individuals, including 4317 cases with insomnia and 3616 controls. MeasurementsSymptoms 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. ResultsAnxiety 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). ConclusionsDifficulties 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.