Pain and sleep may have a bidirectional causal relationship

1. Genetic proxy to insomnia was a risk factor and increased the odds of reporting pain amongst patients in this study across all pain categories (chronic or acute).

2. Conversely, results demonstrated pain to have a lesser, but still a significant effect on insomnia symptoms.

Evidence Rating Level: 1 (Excellent)

Many individuals with chronic pain have reported sleeping disorders, such as insomnia. There appears to be a relationship between insomnia and pain; however, the quality and details of this relationship have yet to be established. Genome-wide association studies (GWASs) allow scientists to identify single-nucleotide polymorphisms (SNPs) and other variants in DNA associated with a disease. The Mendelian method allows a more in-depth study of genes and how exposures can influence their expression. Furthermore, two-sample Mendelian randomization allows to better observe causality between 2 conditions or diseases using genetic information. The aim of this study was to establish a causal bilateral relationship and possible causality between insomnia and pain.

In this study, a two-sample Mendelian randomization analysis was conducted using genetic information from biobanks. Genetic information on pain was drawn from a Finnish biobank with patients who carried an ICD 10 diagnosis code for disorders with an obvious pain component. The genetic pool for insomnia problems was gathered from a British biobank and 23andMe, in which the diagnosis was self-reported. Two-sample Mendelian randomization analysis provided clarity as to which SNPs were significant for pain and insomnia, while further Mendelian randomization analysis allowed to correlate insomnia and pain symptoms with genetic data.

This study showed a bidirectional relationship between insomnia and pain. Symptoms of insomnia acted as a risk factor for developing pain of any subtype: abdominal, general, and articular. Furthermore, pain was shown to have a smaller but significant effect on insomnia symptoms. The results of this study should be taken into consideration while acknowledging its limitations. This study used pain diagnosis data from a data subset that did not differentiate chronic from acute pain, which should be considered when interpreting results. Nonetheless, this study was significant in elucidating a causal relationship between insomnia and pain, suggesting further treatment strategies.

Click to read the study in Sleep

Image: PD

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