Published: 31/03/2023

How Could Sleep Disruption Affect Pain Sensitivity in Healthy Individuals?

Chronic pain is a common and major health burden with estimates suggesting around one-fifth of the global population may be affected. Furthermore, with age being a significant factor in the occurrence of chronic pain, an ageing population could mean that the burden of chronic pain will rise further still. Associated with several symptoms, chronic pain has a considerable impact on quality of life and represents a significant economic burden – comparable to cancer, diabetes, or heart disease.

One symptom that is consistently experienced alongside chronic pain (reported by up to three-quarters of patients) is poor sleep quality. Furthermore, some research suggests that insufficient sleep may contribute to the development and persistence of pain, as well as an increase in systemic inflammation. Patients experiencing chronic pain and poor-quality sleep are often found to have increased pain intensity, more spreading of pain, reduced functional ability, and higher healthcare costs compared to patients who report sleeping well.

To date, sleep provocations are the only models proven to affect central pain mechanisms. Patients with chronic pain most frequently report a disrupted sleep pattern, which may be equally as problematic as short sleep duration but might not compare to experimental models using total sleep deprivation or sleep restriction. Previous studies have linked experimental sleep disruption to signs of central pain sensitisation; however, these studies have implemented extensive sleep disruption and often some degree of sleep deprivation.

There remains a lack of evidence on the effects of prolonged sleep disruption (across consecutive nights) as a model for sensitisation of central pain mechanisms in healthy individuals. A recent study aimed to address this discrepancy by investigating “the effect of three consecutive nights of disrupted sleep on assessments of central pain mechanisms and related cognitive factors.”

Design and Methods of the Study

This study used patient-reported outcome measures (PROMs) to determine how three consecutive nights of sleep disruption affected pain sensitivity using a variety of measures. A total of 30 healthy volunteers aged 18-45 years were recruited to take part in the study through notices on social media, community boards and

PROMs Study Questionnaires

Participants attended an experimental session at baseline (before) and at follow-up (after) disrupted sleep. At these sessions, participants completed several validated questionnaires, including the Pittsburgh Sleep Quality Index (PSQI) to measure subjective sleep quality in one global score; the short form of the International Physical Activity Questionnaire (IPAQ) to measure physical activity levels with higher scores denoting higher levels of physical activity; the Four-Dimensional Symptom Questionnaire (4DSQ) which measures symptoms of somatization, anxiety, depression and distress experienced within the last week; the Positive and Negative Affect Schedule (PANAS) measures positive and negative affect during the past week; and the Pain Catastrophising Scale (PCS) which measures pain-related thoughts and feelings.

Pain Sensitivity and Sleep Disruption Measures

Pain sensitivity assessments were also performed using computer-controlled cuff-pressure algometry and handheld pressure algometry. During the baseline session, participants were instructed on the planned awakenings and were equipped with a Fitbit charge 4 on their non-dominant wrist. The Fitbit device tracks the total time spent asleep, time in bed, and nightly awakenings.
Finally, participants completed a baseline entry in a sleep diary; participants were instructed to complete a sleep diary entry each morning of the study. This was to cover various aspects related to their sleep, including bedtime and time of final awakening; any difficulties falling asleep; how deep their sleep was; the number of awakenings; sleep duration; sleep quality; level of rest.

Results of the Study

Current evidence indicates a bidirectional relationship between sleep quality and pain with sleep disturbances often predicting next-day pain, while current pain can predict sleep disturbances. The current study aimed to disturb sleep continuity to mimic the average number of awakenings experienced by patients with chronic pain.
Participants experienced, on average, 3 awakenings per night. Significantly lower positive PANAS scores were reported after sleep disruption, indicating a lower energy state with engagement. No other questionnaire scores were significantly changed after sleep disruption.

In the current study, sleep disruption was associated with increased measures of central pain sensitisation, expanded pain areas and facilitated temporal summation of pain. Pain assessments indicated a hypersensitivity to pain as well as an increased sensitivity to suprathreshold pressure following sleep disruption.

The researchers note that these findings, which are in line with those previous studies, “emphasise the importance of studying the effect of poor sleep on pain.” They also recommend that future studies further investigate these relationships in patients with chronic pain.

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