0422 The relationship between EEG spectral analysis and pre-sleep cognitive arousal in insomnia disorder

Abstract

Abstract Introduction The hyperarousal model suggests that insomnia is characterized by increased cortical, cognitive, and physiological arousal. However, the relationship between these domains of arousal remains insufficiently studied. The aim of the current observational study was to investigate pre-sleep cognitive arousal, cortical arousal during the night, and the relationship between these domains. Methods 109 patients with insomnia disorder (ID) and 109 age-and gender matched healthy controls (GSC) were investigated on two sleep laboratory nights. As a measure of cortical arousal, EEG spectral power was analyzed during NREM and REM sleep. In addition, participants completed the Pre-Sleep Arousal Scale (PSAS), which consists of a subscale for cognitive arousal (PSAS-CA) and another subscale for self-reported somatic arousal (PSAS-SA). The relationship between the subscale scores and EEG spectral power was calculated by multivariate and univariate analyses of variance. Results The total sample consisted of 218 participants. ID patients had a mean age of 44.7 years (± 10.6 years) and GSC had a mean age of 44.4 years (± 12.6 years). Both groups consisted of 78 women and 31 men.During NREM and REM sleep, patients with ID showed significantly increased spectral power in the EEG gamma band (NREM: p < .001; REM: p = .002). In addition, patients with ID showed significantly increased scores on the PSAS-SA (ID: M = 12.4, SD = 4.4; GSC: M = 10.7, SD = 3.3; t(216) = 3.34, p = .001, d = 0.45) and the PSAS-CA (ID: M = 18.3, SD = 7.2; GSC: M = 10.6, SD = 2.9; t(216) = 10.33, p < .001, d = 1.40). The PSAS-CA score was significantly associated with increased NREM (p = .001) and REM gamma power (p = .004), whereas PSAS-SA was associated with significant decreases in NREM (p < .001) and REM gamma power (p = .001). Conclusion In line with our hypothesis, patients with ID showed increased cortical and cognitive arousal. Moreover, there was a relationship between pre-sleep cognitive arousal and high-frequency EEG activity during the night. This might suggest that the latter is caused (at least in part) by pre-sleep worry and rumination. Support (if any)