Psychological mechanisms in the maintenance of insomnia: arousal, distress, and sleep-related beliefs.

The purpose of this study was to examine whether arousal, distress, and sleep-related beliefs are related to the maintenance of insomnia. From a randomly selected sample from the general population (n=3600), 1936 participants filled out a baseline and 1-year follow-up survey. Logistic regressions were used to investigate whether arousal, distress, and beliefs were related to sleep status (insomnia: n=116; poor sleep: n=222; normal sleep: n=529; good sleep: n=234) over 1 year. Cluster analysis was employed to assess whether it was possible to classify the participants based on their profiles of psychological functioning. The results showed that beliefs in the long-term negative consequences of insomnia, anxiety, depression, and arousal were significantly related to the maintenance of insomnia (18-72% of the variance). Of the individuals with persistent insomnia, 91% belonged to a cluster characterized by high scores on sleep-related beliefs, anxiety, depression, and arousal, and 9% to a cluster defined by low scores on the mechanisms. This study shows that sleep-related beliefs, anxiety, depression, and arousal are related to the maintenance of persistent insomnia, but also that these mechanisms often co-occur in individuals with insomnia.