Sleep and Chronic Pain

I think most of us ask our patients about their quality of sleep. My previous experience in relation to asking this was purely to assist in identifying:

• Inflammatory pain patterns (as mentioned in a previous post).
• Potential “Red Flag” signs.

The more I read about sleep it becomes apparent to me the need to take into account the effects of poor sleep quality and how this can contribute to the pain state.

So how do sleep (or lack there of) and chronic pain interact?

A study by Auvinen et al (2010) found/concluded:

• Insufficient quantity or quality of sleep at the age of 15–16 years predicted Neck Pain and Low Back Pain in girls aged 18–19 years, even after adjustments for determinants and risk factors for these pains, and baseline pain status.
• Insufficient quantity or quality of sleep increases the risk of neck and low back pains independently of depressive mood, physical activity, sedentary behavior, smoking, BMI and parents’ socioeconomic status.
• Insufficient sleep increases the concentration of cytokines and cortisol leading to subsequent activation of  inflammatory mediators.
• Inflammation may mediate the relationship among insufficient quality and quantity of sleep, other psychological risk factors, and neck, shoulder and low back disorders.
• Insufficient quantity and quality of sleep may increase the likelihood of musculoskeletal pains by inhibition of muscle relaxation and activation of the sympathetic nervous system via distress and strain. This may cause increasing levels of muscle tone thus increasing the risk for pain and injuries of muscular origin.
• Sleep disturbances increase the risk of injuries by lowering cognitive function.

The insufficient sleep and subsequent increase in concentrations of cytokines and cortisol is most likely due to increased activation of the Hypothalamo-Pituitary-Adrenal (HPA) Axis (Balbo et al, 2010).

It is of note however that Auvinen et al (2010) suggest:

• That whilst sleep may be a causative factor it may also simply be a mediating mechanism. i.e. the poor sleep may be a result of other factors contributing to the development of pain (e.g. depression, anxiety) and not the causative factor itself.
• The potential mechanisms behind the effect of insufficient quantity and quality of sleep on neck and low back pains are also highly speculative and require further research.
• Intervention studies should be carried out to test whether interventions aimed at improving quality and/or increasing quantity of sleep are effective in the prevention and treatment of musculoskeletal pains.

From the above I think it can be seen how important adequate sleep is and that we don’t just simply consider it in relation to assisting identification of pain patterns/red flags. Poor sleep may be a direct consequence of pain, or may be a pre-existing issue.

How we as physiotherapists (non-pharmacological of course) can assist improving sleep patterns will be a future topic.

I briefly mentioned above the HPA Axis. I think it is important that we have a basic understanding of this subject. The next post will cover this.

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