Introduction: The Cognitive Model of Insomnia by Harvey has gained widespread recognition since 2002 and stimulated treatment development. In short, the model describes how excessive mental focus on sleep creates vicious cycles which maintain insomnia. Little is known about how the model might fit other sleep diagnoses, although the processes are applicable to other somatic disorders such as chronic pain and IBS. The aim of this study was to investigate the degree of insomnia-related processes in other sleep disorders.
Method: Participants (n = 2370) from a randomly selected sample of the general population completed a survey that included five psychological processes as outlined by Harvey (2002): unhelpful beliefs about sleep, monitoring for sleep-related threats, sleep-related safety behaviours, pre-sleep somatic arousal, and sleep-related worry. The following sleep disorders were classified based on the SLEEP-50 questionnaire: apnoea (n = 176), delayed sleep phase (n = 93), insomnia (n = 367), narcolepsei (n = 12) nightmares (n = 84), and PLMS/RLS (n = 184).
Results: The scores on the five processes were significantly elevated for all sleep disorders compared to people without sleep problems.There was a significant positive correlation between presence of sleep disorder and several of the insomnia cognitive processes even after accounting for levels of insomnia. Comorbidity was high in the sample.
Conclusion: This study expands upon Harvey's Cognitive Model of Insomnia by demonstrating its possible applicability beyond insomnia to a range of other sleep disorders. The results indicate that sleep-disturbing processes of insomnia might be applicable in other sleep disorders. The high comorbidity observed in this sample points to the complexity of sleep disorders. Future research should further investigate the mechanisms through which these processes contribute to different sleep disorders.