Abstract:
Aims: An increasing number of studies illustrate the importance of pre-sleep arousal in sleep and chronic pain processes. The aim of this research was to explore how cognitive and somatic pre-sleep arousal relate to sleep, mood, and physical activity. Although hyperarousal is a central component of both insomnia and chronic pain, another aim was to identify any group differences in the mechanisms of these variables and how they relate to sleep. Method: 55 participants were recruited into pain and pain-free insomnia groups for an observational week-long study. Baseline demographic, insomnia, mood and pain data were obtained. Repeated measures of sleep, mood, physical activity, pre-sleep arousal and pain were attained through a daily diary, an Actiwatch and an activity wrist band. Findings: Correlational, t-test, multiple regression, and multi-level analyses for repeated measures were utilised to examine averaged and temporal relationships between variables, and differences between groups. Baseline levels of insomnia, depression, anxiety, stress and worry were similar in both samples. However, there were differences within the daily variables; the pain group had higher somatic pre-sleep arousal levels, less efficient sleep and lower step counts than the insomnia group. Interactions between variables differed; somatic pre-sleep arousal was associated with a larger number of variables, including mood, and had stronger relationships with the variables within the pain group as opposed to the insomnia group. There were also opposite relationships with sleep and physical activity between the groups. Conclusions: The results of this study corroborate previous research findings; cognitive presleep arousal and mood are key variables in insomnia, regardless of whether chronic pain is present or not. However, the findings indicate that mechanisms of insomnia are likely to differ, depending on whether someone has chronic pain or not. These different mechanisms should be explored further in higher powered research, especially somatic hyperarousal, and perceptions of pain, sleep and physical activity within the chronic pain population. Correlational analyses have indicated the need for further research for pain-free insomnia and regular moderateintensity activity to improve sleep, alongside treatment for low mood. On the other hand, the relationships between insomnia and other key variables were much more complex within chronic pain patients; future research could focus on decreasing autonomic and somatic hypersensitivity including anxiety, with additional emphasis on mood.