Poor sleep is known to increase the experience of pain. American researchers investigated the brain mechanisms behind this association. After one night of sleep deprivation, brain activity in pain sensing regions of the cortex increases while activity decreases in areas (striatum, thalamus and insula) that modulate pain processing.
In a laboratory study 25 healthy adults were part of two counterbalanced conditions; one night of sleep or one night of sleep deprivation. After each condition they took part in a thermal pain sensitivity task. Sleep deprivation was found to have a significant impact on pain processing. Sleep-deprived participants registered pain at a significantly lower temperature than sleep-rested participants. Functional magnetic resonance imaging scans revealed that among sleep-deprived participants there was a significant increase in pain reactivity, relative to when sleep rested, within the right primary somatosensory cortex, which is involved in pain processing.
Conversely, in sleep-deprived participants there were significant decreases in brain activity, relative to when sleep rested, in the striatum, thalamus and insula, which are involved in pain valuation. In addition, the extent of expanded reactivity to pain and the associated decrease in thalamic reactivity following sleep deprivation, both predicted increasingly larger sleep-loss related changes in pain thresholds.
In another online study 60 participants, who were currently experiencing pain, completed online assessments of their sleep and pain across two days and nights. Participants who experienced a decrease in sleep efficiency from one night to the next also experienced an increase in pain from one day to the next. Similarly, reductions in sleep quality were associated with increased consequential daily pain. However, nightly changes in total amount of sleep did not predict daily changes in pain.
Thus, better pain management was associated with better quality sleep and spending most of one’s time in bed asleep rather than tossing and turning. In further analyses, the researchers found, that even when controlling for the effects of pain intensity on the first day there was still a significant relationship between sleep quality and pain on the subsequent day. The results suggest that sleep quality is a stronger predictor of subsequent next day pain than prior pain is a predictor of subsequent sleep quality.
Overall, the results of these studies emphasise that even modest improvements in sleep quality may be sufficient to reduce pain intensity. This emphasises the need to consider both when working with patients with sleep and or pain presentations. Helping patients to improve their sleep quality may be an effective part of pain management.
References
Krause, A. J., Prather, A. A., Wager, T. D., Lindquist, M. A., & Walker, M. P. (2019). The pain of sleep loss: A brain characterization in humans. Journal of Neuroscience, 2408-18.
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