Changes in insomnia as a risk factor for the incidence and persistence of anxiety and depression: a longitudinal community study

Abstract

The aim of this investigation was to examine the longitudinal association between change in insomnia status and the development of anxiety and depression in the general population. A survey was mailed to 5000 randomly selected individuals (aged 18–70 years) in two Swedish counties. After 6 months, a follow-up survey was sent to those (n = 2333) who answered the first questionnaire. The follow-up survey was completed by 1887 individuals (80.9%). The survey consisted of questions indexing insomnia symptomatology, socio-demographic parameters, and the Hospital Anxiety and Depression Scale. Change in insomnia status was assessed by determining insomnia at the two time-points and then calculating a change index reflecting incidence (from non-insomnia to insomnia), remission (from insomnia to non-insomnia), or status quo (no change). Multivariate binary logistic regression analyses were used to examine the aim. Incident insomnia was significantly associated with an increased risk for the development of new cases of both anxiety (OR = 0.32, p < .05) and depression (OR = 0.43, p < .05) 6 months later. Incident insomnia emerged also as significantly associated with an elevated risk for the persistence of depression (OR = 0.30, p < .05), but not for anxiety. This study extends previous research in that incidence in insomnia was shown to independently increase the risk for the development of anxiety and depression as well as for the maintenance of depression. The findings imply that insomnia may be viewed as a dynamic risk factor for anxiety and depression, which might have implications for preventative work.