Latest article: Sleep disturbances and chronic pain: The bi-directional relationship

Sleep disturbances such as difficulties falling asleep, staying asleep, and early morning awakening are estimated to affect
30 to 40% of people.¹ People suffering from chronic pain are particularly susceptible, and it is estimated that approximately 75% of adults with chronic pain have concerns about their sleep.²

This is problematic as there is a bi-directional relationship between sleep and pain. That is, having chronic pain can affect sleep quality, and suffering from sleep difficulties can exacerbate pain perception.² Coupled with this is the impact poor sleep can have on lifestyle habits and dietary choices that also affect physical function and pain sensations.^3-5 For example, a poor night’s sleep will make a person feel tired and unrefreshed. This may lead to increased sedentary behaviour, which can worsen pain. Moreover, as one feels tired, they may be more likely to eat processed foods, which can again increase inflammation and pain sensations. People may also choose to isolate themselves because they feel so tired, which can lead to an increased preoccupation with their pain.⁶

PATHOPHYSIOLOGY OF SLEEP DISTURBANCES AND CHRONIC PAIN

Typically, chronic pain is believed to result from tissue injury that leads to excessive and prolonged inflammatory responses. However, the physiology of pain is multifaceted as people with chronic pain can also have alterations in neurotransmitter activity such as serotonin, dopamine, noradrenaline, and glutamate.⁷

Increased oxidative stress is also commonly implicated in chronic pain, as well as disturbances in the activity of the hypothalamus-pituitary-adrenal (HPA) axis, where cortisol production can be either excessive or blunted.^8,9 Interestingly, many of the physiological mechanisms associated with pain have also been identified as having a role in sleep. For example, poor sleep can increase inflammation, reduce antioxidant defences, increase the production of free radicals and disturb the balance of neurotransmitters such as serotonin, dopamine, and noradrenaline.^2,10 These physiological processes are important as they can affect brain wave activity which will alter sleep stage architecture.^11,12