Empirically testing the neurocognitive model of insomnia

• Main Author: Sharman, Rachel
• Other Authors: Ellis, Jason
• Published: Northumbria University 2014
• Subjects: 616.8; C800 Psychology
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639856

The Neurocognitive Model of insomnia proposes that, through conditioned arousal, individuals with insomnia may experience heightened cortical arousal leading to increased sensory processing of external stimuli and sleep state misperception. This thesis provides a novel contribution to the literature by utilising auditory stimuli to examine the propositions of the Neurocognitive Model as a method of both eliciting and measuring the effects of cortical arousal. Firstly, the effect of noise on sleep was observed within the habituated home environment, evidencing that NREM sleep may be more susceptible to increased arousal through noise comparative to REM. Furthermore, traits typically associated with insomnia showed relationships with sleep disturbance due to noise, indicative that noise may increase cortical arousal. Secondly, the administration of novel noise in a non-habituated laboratory environment was utilised to raise cortical arousal levels in good sleepers to directly test the propositions of the Neurocognitive Model. Results demonstrated that noise altered both subjective and objective sleep along with creating a misperception of sleep onset, albeit not associated with explicit memory of noise stimuli. Finally, utilising individuals assumed to be experiencing heightened cortical arousal (insomnia) and good sleepers, words were administered during sleep onset periods to directly assess the processing and misperception components of the Neurocognitive model. Results demonstrated that both explicit and implicit recognition for words presented during sleep was greater for individuals with insomnia, yet this did not associate with a misperception of sleep. Therefore, this thesis proposes that the Neurocognitive Model could be a model of the effects of raised cortical arousal on sleep of which the two outcome pathways are the processing of auditory stimuli and sleep state misperception. Future research may wish to continue to examine the role of cortical arousal in the context of the Neurocognitive Model as a potential mechanism of sleep state misperception in those with insomnia and vulnerable good sleepers.