Objectives: This study investigated the bidirectional relationship between intensity of low back pain (LBP) and sleep disturbance. Further, the study aimed to determine whether any relationship is dependent on pain duration, symptoms of depression and anxiety and the method of sleep assessment (subjective vs. objective).
Methods: Eighty patients with LBP completed a sleep diary. A sub-group of 50 patients additionally wore an electronic device (Armband) to measure sleep for 7 consecutive days. Pain intensity was assessed twice daily using a sleep diary. Depression and anxiety symptoms were assessed at baseline using the Depression Anxiety Stress Scale (DASS-21) questionnaire. Generalised estimating equations (GEE) with an exchangeable correlation structure were used to examine the relationship between day-time pain intensity and sleep.
Results: The GEE analysis showed that a night of poor sleep quality, difficulty falling sleep (assessed by the sleep diary), waking after sleep onset and low sleep efficiency (assessed by the sleep diary and Armband) were followed by a day with higher pain intensity. Further, a day with higher pain intensity was associated with a decrease in the subsequent night's sleep quality, an increase in sleep latency (assessed by the sleep diary), waking after sleep onset (assessed by both measures) and low sleep efficiency (assessed by the Armband).
Discussion: The findings demonstrate that there is a bidirectional relationship between sleep and pain intensity in patients with LBP. The relationship is independent of pain duration and baseline symptoms of depression and anxiety and somewhat dependent on the method of sleep measurement (sleep diary or Armband). Future research is needed to determine whether targeting sleep improvement in patients with LBP contributes to pain reduction.
(C) 2014 by Lippincott Williams & Wilkins