Insomnia is commonly comorbid with chronic pain, and typically leads to worse outcomes. Two factors that could contribute to a cycle of pain and sleeplessness are pre-sleep cognitive arousal (repetitive thought processes) and low mood. This study aimed to examine how pain, sleep disturbance, mood, and pre-sleep cognitive arousal inter-relate, to determine whether low mood or pre-sleep cognitive arousal contribute to a vicious cycle of pain and insomnia.
Forty seven chronic pain patients completed twice daily diary measures and actigraphy for one week. Analyses investigated the temporal and directional relationships between pain intensity, sleep quality, time awake after sleep onset, anhedonic and dysphoric mood, and pre-sleep cognitive arousal. Fluctuations in predictor variables were used to predict outcome variables the following morning using mixed-effects modelling.
For people with chronic pain, an evening with greater pre-sleep cognitive arousal (relative to normal) led to a night of poorer sleep (measured objectively and subjectively), lower mood in the morning, and a greater misperception of sleep (underestimating sleep). A night of poorer sleep quality led to greater pain the following morning. Fluctuations in pain intensity and depression did not have a significant influence on subsequent sleep.
For people with chronic pain, cognitive arousal may be a key variable exacerbating insomnia, which in turn heightens pain. Future studies could target cognitive arousal to assess effects on sleep and pain outcomes.
NOTE: This study used the CamNtech Actiwatch 7 (AW7) which was discontinued in 2012 – Direct replacement is MotionWatch 8.