DENVER — The presence of a psychiatric disorder did not appear to influence relationships between pain and sleep, researchers reported here.
Sleep and pain were significantly correlated and their association was similar regardless of whether a patient had a psychiatric diagnosis, according to a poster presentation by Samir Sethi, MD, of George Washington University School of Medicine in Washington, D.C., and colleagues, at the 2019 American Academy of Pain Medicine meeting.
“Our research shows there is a relationship between sleep and pain that is not influenced by underlying psychiatric or sleep disorders,” Sethi told MedPage Today.
“Our goal is to understand more about the complex relationship between sleep and pain,” he added. “There is little research about how to treat insomnia in the chronic pain patient population, and we plan to further understand what affects the pain-sleep relationship.”
Recent literature suggests that sleep disturbance is one of the most prevalent complaints among chronic pain patients, he added. Evidence indicates pain and sleep are related, although questions about the causality and mechanisms remain.
Some researchers propose that pain and sleep have a bidirectional relationship. Population-based longitudinal studies have reported that sleep impairment predicts new incidents of chronic pain; smaller studies have demonstrated that sleep quality is a stronger predictor of pain than vice versa.
In the new study, Sethi and co-authors surveyed 91 patients (26 men and 65 women) from the George Washington University Spine and Pain Center about their pain and sleep habits, using the Brief Pain Inventory and the Insomnia Severity Index.
The Brief Pain Inventory is a self-administered validated survey that classifies pain severity on a scale of 0 (no pain) to 10 (worst imaginable pain) and assesses how pain interferes with a patient’s daily life. The Insomnia Severity Index reflects a patient’s perceived insomnia severity, focusing on problems both with falling asleep and staying asleep. Scores range from 0 to 28, with 0 representing no clinically significant insomnia and 22-28 indicating severe clinical insomnia.
The researchers grouped patients by the presence or absence of psychiatric diagnosis. In the data analysis, the team incorporated worst, lowest, average, and current pain scores from the Brief Pain Inventory, and falling asleep, staying asleep, and waking up too early scores from the Insomnia Severity Index.
In this study, patients were an average age of about 56 and had a mean Insomnia Severity Index score of 13.7 — indicating mild to moderate insomnia — and a mean pain rating of 6.0.
As expected, the researchers found a statistically significant correlation between the Brief Pain Inventory and Insomnia Severity Index (r=0.41; P<0.0001). Each one-point increase in average Brief Pain Inventory scores was associated with a 1.2 point rise in the Insomnia Severity Index.
When the pain-sleep relationship was compared with the presence or absence of an underlying psychiatric disorder, the outcome did not change: the pain-sleep association was similar regardless of psychiatric diagnosis.
While this analysis sheds light on the role of psychiatric disorders in the pain-sleep connection, future studies are needed to understand more about how sleep and chronic pain may influence each other, Sethi noted.
The study had several limitations, the team said, including the small sample size and the fact that insomnia severity was self-reported. Unknown confounders, including the use of medication, also may have affected the results.
Sethi reported no conflicts of interest.