Objectives: There are strong links between sleep and psychotic-like experiences (PLE), such as magical ideations or persecutory ideas. Sleep disturbances seem to play an important role in the occurrence of such symptoms, but studies investigating PLE in patients with sleep disorders are lacking.
Methods: We studied 24 subjects with insomnia disorder (41 ± 13 years) and 47 participants with obstructive sleep apnea (OSA, 47 ± 11 years) in the sleep laboratory and 33 healthy controls. Sleep in patients with sleep disorders was recorded and scored according to standard criteria of the American Academy of Sleep Medicine. PLE were measured by the Magical Ideation Scale (MIS, short form with 10 items) and by the Peters et al., Delusions Inventory (PDI, 21 items). Additionally, cognitive tests and further psychological self-rating tests such as the Beck Depression Inventory (BDI) and the Pittsburgh Sleep Quality Index (PSQI) were administered.
Results: Patients with insomnia had significantly higher scores of magical and delusional ideations compared to healthy controls. Sleep apnea patients showed a tendency of a higher score of delusional beliefs in comparison to controls. Magical ideations in insomnia subjects were significantly negatively correlated with the number of sleep spindles. In a subgroup of insomnia patients without antidepressants, delusional beliefs were negatively associated with rapid eye movement (REM)-sleep.
Conclusions: As there are indications that diminutions of sleep spindles are a biomarker for dysfunctional thalamo-cortical circuits underlying the neuropathology of psychosis, we conclude that there might be a sub-group of insomnia patients with fewer sleep spindles which is more vulnerable to developing a psychotic disorder in the future.
Keywords: Insomnia; Psychosis; Sleep apnea; Sleep disorder; Sleep spindle.
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