On the relationship between EEG spectral analysis and pre‐sleep cognitive arousal in insomnia disorder: towards an integrated model of cognitive and cortical arousal

Abstract

Summary According to the hyperarousal model, insomnia is characterised by increased arousal in the cortical, cognitive, and physiological domains. However, the interaction between these arousal domains is poorly understood. The present observational case–control study aimed to investigate cortical arousal during the night, pre‐sleep cognitive arousal and the relationship between these two domains. A total of 109 patients with insomnia disorder (ID) and 109 age‐and gender matched healthy controls were investigated on two sleep laboratory nights. Electroencephalographic (EEG) spectral power during non‐rapid eye movement (NREM) and REM sleep was analysed as a measure of cortical arousal. In addition, patients completed the Pre‐Sleep Arousal Scale (PSAS), which consists of two subscales, one for cognitive arousal (PSAS‐CA) and one for self‐reported somatic arousal (PSAS‐SA). The relationship between the subscale scores and EEG spectral power was calculated by multi‐ and univariate analyses of variance. During NREM and REM sleep, patients with ID showed significantly increased spectral power in the EEG gamma band. In addition, patients with ID showed significantly increased scores on both subscales of the PSAS. The PSAS‐CA score was significantly associated with increased NREM and REM gamma power, whereas PSAS‐SA was associated with decreases in NREM and REM gamma power. Consistent with our hypothesis, patients with ID showed increased cortical and cognitive arousal. Moreover, there was an association between these two arousal domains, which may indicate that cortical arousal during the night is (at least in part) elicited by pre‐sleep worry and rumination.

Hyperarousal in insomnia disorder: Current evidence and potential mechanisms

“…It is possible that it is an epiphenomenon of various processes that in turn determine its maladaptive character. Consistent with this, Dressle et al (2023) were able to show a relationship with maladaptive pre-sleep cognitive arousal. In contrast to more adaptive cognitive processes as a result of mindfulness-based therapy, maladaptive cognitions that extend into sleep could contribute to the subjective impression of wakefulness and thus to paradoxical insomnia (Dressle et al, 2023;Feige et al, 2008).…”

“…Because gamma power has been associated with cognitive control (Cho et al, 2006; Minzenberg et al, 2010), the effect of cognitive arousal on gamma power could also be influenced by applying cognitive control. Dressle et al (2023) further speculate that these different types of cognitive processing might have different effects on sleep. More precisely, verbal cognitive arousal might primarily affect the microstructure of sleep.…”

“…One of the most frequently used measures is the Pre-Sleep-Arousal Scale (PSAS), which consists of a subscale for selfreported cognitive and another subscale for self-reported somatic arousal (Nicassio et al, 1985). Indeed, numerous studies have demonstrated that patients with insomnia show increased pre-sleep cognitive activity compared with good sleeper controls (Dressle et al, 2023;Hertenstein et al, 2015;Kalmbach et al, 2020;Nicassio et al, 1985;Palagini et al, 2016Palagini et al, , 2017Robertson et al, 2007;Vochem et al, 2019). In accordance with the concept of 24-hr hyperarousal, this increase in cognitive activity also occurs during the day (Harvey, 2002;Kallestad et al, 2010;Palagini et al, 2015).…”

“…A lack of cognitive capacity, in turn, could lead to more imagery-based thinking, which has the opposite effect of increasing negative emotions and physiological arousal Vasey et al, 2017). Dressle et al (2023) found that pre-sleep cognitive arousal was positively, whereas self-reported somatic arousal was negatively associated with gamma power during sleep. Because gamma power has been associated with cognitive control (Cho et al, 2006;Minzenberg et al, 2010), the effect of cognitive arousal on gamma power could also be influenced by applying cognitive con- It can be generally concluded that cognitive-emotional hyperarousal is central to the pathophysiology of insomnia.…”

“…trol Dressle et al (2023). further speculate that these different types of cognitive processing might have different effects on sleep.…”