Sensory gating in primary insomnia

Abstract

Although previous research indicates that sleep architecture is largely intact in primary insomnia (PI), the spectral content of the sleeping electroencephalographic trace and measures of brain metabolism suggest that individuals with PI are physiologically more aroused than good sleepers. Such observations imply that individuals with PI may not experience the full deactivation of sensory and cognitive processing, resulting in reduced filtering of external sensory information during sleep. To test this hypothesis, gating of sensory information during sleep was tested in participants with primary insomnia (n = 18) and good sleepers (n = 20). Sensory gating was operationally defined as (i) the difference in magnitude of evoked response potentials elicited by pairs of clicks presented during Wake and Stage II sleep, and (ii) the number of K complexes evoked by the same auditory stimulus. During wake the groups did not differ in magnitude of sensory gating. During sleep, sensory gating of the N350 component was attenuated and completely diminished in participants with insomnia. P450, which occurred only during sleep, was strongly gated in good sleepers, and less so in participants with insomnia. Additionally, participants with insomnia showed no stimulus-related increase in K complexes. Thus, PI is potentially associated with impaired capacity to filter out external sensory information, especially during sleep. The potential of using stimulus-evoked K complexes as a biomarker for primary insomnia is discussed.

REM sleep as a potential indicator of hyperarousal in psychophysiological and paradoxical insomnia sufferers

“…In sum, the small difference between groups on objective SE could explain the absence of significant differences between GS, PSY-I and PARA-I for the amount of REM sleep in our investigation. Although differences in REM sleep macrostructure of INS compared to GS were observed in the majority of previous studies, our results are similar to those of Hairston et al (2010). Finally, the number of REM sleep periods and their duration were similar between groups.…”

“…In general, INS' nights were characterized by a significantly smaller proportion of REM sleep compared to good sleepers (GS; Bonnet and Arand, 1995;Feige et al, 2008;Jurysta et al, 2009;Merica et al, 1998;Nissen et al, 2011;Voderholzer et al, 2003). Nonetheless, opposite results were also observed, thus that INS spent more time in REM sleep than GS (Lamarche and Ogilvie, 1997;Okura et al, 2008) or no differences at all (Hairston et al, 2010). Altogether, results tend to imply a lower proportion of REM sleep in INS compared to GS .…”

Increased insula coactivation with salience networks in insomnia

“…Insomnia is associated with psychiatric conditions, including anxiety and major depression, and in this sample insomniacs have increased anxiety and depression scores compared to healthy controls, albeit below clinical thresholds. The increased insula coactivation observed could be indicative of this subthreshold anxiety, worry and rumination, or a signature of insufficient gating of the sensory stimuli of the fMRI environment (Hairston et al, 2010). However, another intriguing mechanism by which the insula may contribute to insomnia is through the subjective perception of sleep distress.…”

More Severe Insomnia Complaints in People with Stronger Long-Range Temporal Correlations in Wake Resting-State EEG

“…This imbalance manifests as a shift in power from lower to higher frequency oscillations in resting state electroencephalography (EEG) (Wolynczyk-Gmaj and Szelenberger, 2011; Corsi-Cabrera et al, 2012; Colombo et al, 2016). It moreover manifests as reduced gating and heightened sensory reactivity in response to exogenous (Yang and Lo, 2007; Bastien et al, 2008; Hairston et al, 2010; Kertesz and Cote, 2011) and endogenous stimuli (Wei et al, 2016). …”