Abstract
It is clinically and theoretically plausible that insomnia contributes to the development and maintenance of paranoid fears. The primary aim of the study was to establish in a large sample whether insomnia and paranoia are associated more strongly than by chance. Cross-sectional data on paranoia, insomnia, anxiety, worry, depression, irritability, and cannabis use were obtained from the second British National Survey of Psychiatric Morbidity, a general population survey of adults aged 16–74 years living in Great Britain (N = 8580). It was found that insomnia was associated with an approximately two to threefold increase in paranoid thinking. Paranoia and insomnia were both strongly associated with the presence of anxiety, worry, depression, irritability and cannabis use. In a path analysis the association of paranoia and insomnia was partially explained by the affective symptoms, and, to a much lesser degree, cannabis use. The results are consistent with recent developments in the cognitive understanding of persecutory delusions, in which insomnia, negative affect, and substance use are identified as key factors. Longitudinal studies of insomnia and paranoia, and tests of the effects of sleep interventions on levels of paranoia, are now required to examine causality.
Highlights
Difficulties in falling or staying asleep are common
Sleep difficulties were present in 3380 participants, insomnia of at least moderate severity in 1120 participants, and chronic insomnia in 623 participants
While paranoia decreased with age
Summary
30% of the general population experience current symptoms of insomnia, with a third of this group having chronic insomnia (Ohayon, 2002; Walsh, 2004; Morin et al, 2006; Stewart et al, 2006). It is only in the last few years that it has been recognised that paranoid thinking is almost as prevalent. At least 25% of the general public regularly experience paranoid thoughts, and the lifetime prevalence of persecutory delusions is approximately 5% (Freeman and Freeman, 2008; Rutten et al, 2008) Both insomnia and paranoia have been linked with negative affect. Sleep difficulties are a risk factor for developing emotional disorders such as anxiety and depression (Ford and Kamerow, 1989; Breslau et al, 1996; Morphy et al, 2007), while negative affective states predict the occurrence of paranoid thinking
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