Introduction
For most of time it has been thought that increased pain levels lead to poor sleep, but the total body of research over the past decade is beginning to indicate increased pain and poor sleep is a bidirectional relationship. In the past two years, the paradigm is shifting further to indicate that poor sleep is becoming more of the casual factor in the relationship, and it is less reciprocal than what was originally thought. What this means is that a lack of sleep or poor sleep quality leads to increased pain sensitivity, not just the other way around. Up to 56% of adults in the United States report difficulty in falling asleep, difficulty staying asleep, or overall inadequate levels of sleep. 88% of people with chronic pain in the US report some form of sleep disturbances. The goal of this study was to examine the effect of sleep on persistent knee pain and multisite pain.
Methods
This longitudinal study consisted of adults ages 50-80 in Australia, with follow ups and tracking performed at 2.6 years, 5.1 years, and 10.7 years. 1,100 participants were recruited and 533 were traced and tracked through the completion of the entire study. Pain measurements were assessed subjectively through specific questionnaires for knee pain severity (WOMAC) and questioning if a person had any form of pain in 2 or more locations, and objectively through x-rays of the bilateral knees.
Results
Over the 10.7 year period of the study, 533 participants completed all follow up reporting. Overall, these participants reported consistent knee pain and MSP, and the number of individuals reporting sleep difficulties was comparable at year 10 compared to onset of the study. In looking back at the data, WOMAC knee pain scores and multisite musculoskeletal pain worsened in correlation to the extent of sleep disturbances. An interesting breakdown of the participants who completed the full study, indicated that the participants who fell off after 2 and 5 years had comorbidities consisting of greater body mass index, less physical activity, greater overall pain scores, and higher levels of smoking, being unemployed, and taking pain medication.
Discussion & Conclusion
This is the first study of its kind to follow participants long term, and utilize objective measurements to get results. Simply stated, sleep disturbance was independently associated with an increase in pain severity, without a placebo effect. Unfortunately, what this study also shows is that once a person falls into poor sleep quality and increased pain levels, rarely does either improve over a 10-year period. According to the authors, what this tells us is that treating poor sleep quality or pain has a reciprocal effect and could help the other. Also, co-morbidities such as higher body weight, smoking, unemployment, and educational levels are variables associated with poor sleep and higher pain levels. Also, those with consistently poor sleep quality have higher levels of CRP (c-reactive protein) and IL-6, which are both objective measures of systemic inflammation, a common pathway for pain in the body.
Physical Therapy First Implications
As the primary provider for Musculo-skeletal related pain and injuries, the physical therapists at Physical Therapy First can help you create healthy sleep habits and patterns which will in turn improve your overall sense of pain. An improvement in pain sensitivity leads to an improvement in function, and will help you get back to the lifestyle you enjoy, pain free. At Physical Therapy First, our Doctors of Physical Therapy provide one on one treatments for one hour to assist you in making the improvements from where you are now to where you want to be regarding your pain.
Reference:
Pan, F., Tian, J., Cicuttini, F., Jones, G. (2020). Sleep Disturbance and Its Association with Pain Severity and Multisite Pain: A Prospective 10.7-Year Study. Pain Therapy. 9:751–763