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Research Review By Dr. Shawn Thistle©


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Date Posted:

October 2011

Study Title:

The association between chronic low back pain and sleep – A systematic review


Kelly GA, Blake C, Power CK et al.

Author's Affiliations:

UCD School of Public Health, Physiotherapy and Population Science, University College of Dublin, Ireland

Publication Information:

Clinical Journal of Pain 2011; 27: 169-181.

Background Information:

It is well known that LBP, particularly the chronic variety (CLBP), represents a significant clinical, economic and societal issue. As manual therapists, we normally focus on the mechanical or physical aspects of CLBP, yet this condition can affect many aspects of a patient’s life in addition to physical function, such as work capacity, psychological well-being, and sleep. In fact nearly 50% of CLBP patients report sleep disturbance (1, 2), a general term which can encompass:
  • Poor sleep quality
  • Reduced sleep efficiency (ratio of sleep time : time in bed)
  • Reduced sleep duration
  • Delayed sleep onset (time to fall asleep)
  • Fragmentation of sleep architecture (alteration of REM stages)
  • Increased activity or movement during sleep
  • Non-restorative sleep
The importance of sleep to human function is obvious – restoration, growth and energy conservation. However, many people experience sleep disorders. Recent evidence from the US shows that 29% of workers report becoming very sleepy or falling asleep at work, while 12% have been late for work due to lack of sleep (3). From a clinical perspective, there is abundant research showing that pain is increased when sleep is deprived. This can result in a deteriorating cycle (similar to a ‘pain-spasm’ cycle): increased pain leads to diminished sleep which leads to increased pain, and so on. To compound this, pain medications, such as opioids, are known to adversely affect sleep architecture (4).

Therefore, the management of any chronic pain syndrome, including CLBP, should include a strategy to address sleep disturbance. Typically, sleep research has focused on chronic pain populations such as fibromyalgia, irritable bowel syndrome, osteoarthritis, cancer pain, headache/migraine and chronic fatigue syndrome patients. This systematic review aimed to determine the relationship between sleep and CLBP and discussed directions for future research.

Pertinent Results:

17 articles fulfilled the inclusion criteria – 14 quantitative and 3 qualitative. Of the quantitative studies, 3 were rated as weak, 10 as moderate and 1 as strong quality. All 3 qualitative studies were rated as ‘strong’ in quality. Review of the results of these studies revealed:
  • CLBP relates to many aspects of sleep including: sleep disturbance and duration (15 studies), sleep affecting daytime function (5 studies), sleep quality (4 studies), ability to fall asleep (3 studies) and activity during sleep (3 studies)
  • Consistent evidence demonstrated that CLBP was associated with greater sleep disturbance, reduced sleep duration and quality, increased time to fall asleep, poor daytime function and greater sleep dissatisfaction and distress
  • Inconsistent evidence was found for an adverse association between CLBP and sleep efficiency and activity
Sleep Disturbance & Duration:
Consistent evidence from 13 studies of moderate quality (Level B) supported the adverse relationship between CLBP and sleep disturbance including: generally reported disturbance, decreased total sleep time, increased frequency of awakening during the night and time spent awake after sleep onset. Only 2 studies, also of moderate quality, refuted these findings.

Sleep Affecting Daytime Function:
Consistent evidence from 5 qualitative studies (moderate quality, Level B) found that poor sleep was adversely associated with daytime function including: general reduction in function, increased daytime sitting, lying and napping, pronounced sleepiness/exhaustion and general interference in function.

Sleep Satisfaction & Distress:
4 subjective studies (Level D evidence) provided consistent evidence that LBP patients report reduced satisfaction and increased distress caused by sleep problems.

Sleep Quality:
Consistent evidence from 4 moderate quality studies (Level B) found that CLBP was associated with poor sleep quality with depressed LBP patients exhibiting further disruptions.

Ability to Fall Asleep:
Consistent evidence from 3 low quality studies (Level C) found that CLBP patients had trouble falling asleep compared to controls. Delayed sleep onset was also associated with higher pain levels.

Sleep Efficiency:
Inconsistent, Level D evidence provides no firm conclusions. More research is needed in this area.

Activity During Sleep:
Inconsistent evidence from 3 objective studies (Level D) suggested that further research is required to assess the association between CLBP and greater movement during sleep (which correlates with less restful sleep).

Clinical Application & Conclusions:

With roughly 50% of CLBP patients reporting sleep disturbance, it is still unclear if a cause and effect relationship exists even after examining the results of this review. In the general population, sleep disturbance and CLBP are common so it is no surprise that two may coexist.

This is the first systematic review to investigate the relation between CLBP and sleep and the authors should be commended for this. An important take-home message from this systematic review is that practitioners dealing with CLBP patients should ask their patients about sleep and attempt to assist those in need with this aspect of their lives. It should be noted that the efficacy of various interventions for managing sleep disturbance requires further study and was not the focus of this review.

From a practical perspective, most of us would agree that patients in any sort of pain heal faster or turn a major corner once their sleep normalizes. This study validates this observation and paves the way for more research in this area which will better equip us to manage CLBP in a holistic manner.

Study Methods:

This systematic review consisted of 3 phases:
  1. A search of electronic databases (PubMed, Cinahl Plus, EMBASE, PsychInfo, Pedro, Cochrane Library)
  2. Screening of applicable articles by two reviewers
  3. Rating of internal validity and strength of evidence
It is important to note that this systematic review included studies of mixed methodologies. That is, both quantitative and qualitative research was included. Based on the topic at hand, I think this was an appropriate approach despite the fact that it makes statistical combination and synthesis more difficult.

Inclusion criteria for the studies in this review were:
  • Involving adults 18+ years of age, published between 1970-2009 and written in English
  • Relating to chronic LBP: “pain which has persisted beyond the normal tissue healing time”, persisting for > 12 weeks
  • Investigating the relationship between CLBP and sleep, or CLBP studies where sleep was an outcome measure
  • All study types were eligible: RCT, case-control, longitudinal, cohort, qualitative, case studies etc.
Two appraisal tools were selected to assess the internal validity and quality of the studies:
  1. The Effective Public Health Practice Project (EPHPP) quality assessment tool – 6 items that assess selection bias, allocation bias, confounders, blinding, data collection, withdrawals and drop-outs; and
  2. The Critical Appraisal Skills Programme (CASP) quality assessment tool – 10 questions addressing research method vigor.

Study Strengths / Weaknesses:

Study Strengths:
  • Unique approach for a systematic review by including qualitative and quantitative research together – again, I feel this is appropriate because sleep quality is, in large part (and aside from neurophysiological measures), quite subjective/qualitative
  • This is (to my knowledge) the first attempt at synthesizing the literature on this topic
  • Due to the inclusion of qualitative literature, the authors were unable to conduct a meta-analysis or calculate effect sizes
  • Some of the included studies used “sleep quality” as a general outcome whereas others broke sleep quality into more detailed components – this represents and inconsistency and weakness in this literature that could be improved upon in future work

Additional References:

  1. Marin R, Cyhan T, Miklos W. Sleep disturbance in patients with chronic low back pain. Am J Phys Med Rehabil 2006; 85:430–435.
  2. Tang NK, Wright KJ, Salkovskis PM. Prevalence and correlates of clinical insomnia co-occurring with chronic back pain. J Sleep Res 2007; 16:85–95.
  3. MacIntyre J. Lack of sleep affects employees’ work. Available at: http://the.honoluluadvertiser.com/article/2008/Mar/23/bz/hawaii803230343.html. [Accessed January 2009]
  4. Shaw IR, Lavigne G, Mayer P, et al. Acute intravenous administration of morphine perturbs sleep architecture in healthy pain-free young adults: a preliminary study. Sleep 2005; 28:677–682.

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